Egg White

Eggs are used to add viscosity and mouthfeel to cocktails, sour cocktails like Whisky Sour, tastes the best when made with added egg white. Egg whites create a creamy texture and a thick layer of foam on top of a cocktail. While unlike using just the white, adding the yolk adds a bit of a flavour to the drink, it helps emulsify the other ingredients and adds the eggnog flavour to your cocktail.
To get the silk smooth texture and mouthfeel and the foamy head without weakening the drink by melting the ice from too long shaking, which is needed to break the proteins of the egg white to froth up, dry shake the ingredients first, that is, pour all ingredients and the egg white in your shaker and shake hard without ice first, for about a minute and then add ice and shake again.

Evaporated Milk

Milk can do wonders to your regular cocktail. For a rich creamy cocktail, milk does wonder .You may argue that milk as it is made of fat, and being low in acid, will easily curdle if its mixed with alcohol.
Best way to get a rich and creamy cocktail is to use bourbon, milk will soften its whiskey flavour. If you are looking for some spicier yet creamy cocktail go for Scotch with milk cocktails, they'll surely set you holiday mood.

Chocolate Syrup

Cola in general is a carbonated soft drink flavoured with vanilla,cinnamon, nutmeg, citrus oils and other flavourings and has been popular ever since it's invention by Pharmacist John Pemberton in 1886.

Cola gets it's name from the Kola Nut from which a Cola gets it's caffeine, the original recipe of Pemberton contained cocaine from coca leaves too, and was an non-alcoholic wine. Since it's invention the recipe has been closely guarded and yet replicated by many other brands of which, Pepsi Cola remain to be the major competition of Coca Cola invented and trade marked by Pemberton.

Cola being sweet and having a refreshing flavour profile that includes vanilla on top to a citrus taste with complex flavours of nutmeg, cinnamon and other very oriental herbs, it in itself is a great mixer for so many spirits. Best of course is the neutral Vodka but who doesn't want a Rom and Coca Cola? and have not heard the Andrew Sister's Song Rum and Coca Cola

Note: If you are one of those that are clinically dependent on Coca Cola or Cola in general and drink litres of Cola per day, the SodaStream Diet Cola will be a great alternative for you. It has less sugar and uses sucralose instead of aspartame used in Diet Cola. Each bottle makes 9 litres of Cola. Note that you need the Sodastream Sparkling Water Maker for this. But it's worth the money.

Vanilla Extract

Vanilla is a spice derived from orchids of the genus Vanilla, the spice is obtained from the pods of the Mexican species of flat leaved Vanilla. The characteristic flavour of Vanilla comes from the aromatic compound Vanillin. Up to 85% of a vanilla essential oil is Vanillin.
Natural vanilla flavour is in pure form, a little more complex than plain Vanillin, but most of the times the Vanillin is what is needed to release that familiar flavour in a drink.
Note that when a drink asks for Vanilla extract, it means an extract of real Vanilla from Vanilla pods in an alcoholic suspension and is usually less processes and stronger, while Vanilla Flavour or Vanilla Essence is a processed product made using artificial flavours and colours. While a Vanilla syrup is a sweetened thick condiment with either real organic vanilla flavour or artificial vanilla flavouring.
The thumbs rule is, if you run out of Vanilla extract, go for Maple syrup as a replacement. Also note that artificial vanilla is strong and artificial vanilla flavour comes from Castoreum, a chemical compound that comes from a beaver's castor sacs, which are located between the pelvis and the base of the tail.

Lemon Juice

Lemon Juice being rich in Vitamin C is an excellent remedy for sore throat and aids in digestion and controls blood sugar, and also promoted weight loss. It is used for various culinary and non-culinary purposes all over the world. Lemon juice is known to reduce or even reverse the effects of excessive alcohol consumption and intoxication.
In drink mixing, fresh lemon juice brings a tangy zing to so many classic drinks and in fact, it's the most used ingredient in drink mixing other than the liquors of course.

Instant Coffee

Coffee or roasted coffee beans brewed in hot water, is the most popular drink that probably competes only with tea in the non-alocholic beverages category. Coffee being a rich source of caffeine it can help the human body overcome fatigue and improve physical performance and also lower risks of several conditions like Type II Diabetes, Cancer and Alzheimer's and Parkinson's disease.
Coffee liqueur is a popular and brands like Kahlua and Tia Maria are regulars in cocktails, but often brewed non alcoholic coffee is used in cocktails too, hot black coffee with Rum and whipped cream is what makes a Troical Coffee Cocktail for you, and being a caffeine rich liquid, it is a strange combination with alcohol since it tends to interact with the body and do just the opposite of what alcohol does, that it, tries to keep you alert and awake.

Sugar

Brown Sugar is a sucrose sugar with a distinctive brown colour from the presence of molasses, it is a partially refined or unrefined sugar containing sugar crystals and residual molasses giving it a distinctive taste and flavour of crystallised molasses or toffee. The taste of dark brown sugar is described as a caramel taste with a deep molasses flavour.
Brown sugar is used in cocktails where a caramel candy or toffee flavour is expected.

Caster Sugar is finely ground granulated sugar. It is not as fine a powdered confectioners' sugar and has a little grit to it. It is somewhere between confectioners' sugar and granulated sugar, and melts in mouth with a mild spicy feel to the tongue

Vanilla Sugar is the regular granulated sugar infused with vanilla flavour, by using vanilla pods and seeds to flavour the sugar. A home made alternative is to use vanilla sticks or pods in a jar of sugar and leave it sealed for 4 weeks to allow the vanilla flavour to infuse. Or to use granulated sugar and vanilla extract and blend in a mixer, although this ends up in powdered sugar.

Irish Whiskey

Irish Whiskey or Uisce Beatha ( same as French Eau de vie or Water of Life ) was the most popular spirit of the world once,
Irish Whiskey was one of the earliest distilled drinks in Europe, it is believed that the Irish Monks brought the technique of perfume distillation back to Ireland from Southern France and modified that to distill drinkable alcohol. The early Irish Whiskey was not what it is today and it was more a distilled whiskey infused with herbs such as thyme, anise or mint.

Irish Mist is a whiskey liqueur created using one such original recipe, but by current standards, although it is created just like early Irish Whisky was made with herbal infusions, it'll be categorised as a liqueur.

Although it seems like Whiskey has been produced in Ireland since 1000 CE but the first written record of it can be found from 1405 in the Annals of Clonmacnoise, that is a good 89 years before Scotland.

Irish Whiskey has a smoother finish as opposed to the smoky, earthy overtones of a Scotch. The smoky overtones in Scoth comes from drying the malted barley using peat smoke, but peat is rarely used in the malting process in Ireland, leaving a few like Connemara peated Irish malt whiskey and Pearse Whiskey.