Preheat oven to 180 C / Gas mark 4. In a large bowl, mix together the biscuit crumbs, icing sugar and 5 tablespoons cocoa. Add melted butter and stir until well mixed. Pat into the bottom of a 23cm loose-bottomed or springform cake tin. Bake in preheated oven for 10 minutes; set aside. Increase oven temperature to 230 C / Gas mark 8.
In a large bowl, combine cream cheese, caster sugar, 4 tablespoons cocoa and flour. Beat at medium speed until well blended and smooth. Add eggs one at a time, mixing well after each addition. Blend in the soured cream and Baileys liqueur; mixing on low speed. Pour filling over biscuit base.
Bake at 230 C for 10 minutes. Reduce oven temperature to 120 C / Gas mark 1/2 and continue baking for 60 minutes.
With a knife, loosen cake from sides of tin. Allow to cool slightly, then push up base of the tin to remove cheesecake. Chill before serving. If your cake cracks, a helpful tip is to dampen a palette knife and smooth the top, then sprinkle with some biscuit crumbs.
Made two cheesecakes using this recipe. On the first, I followed the baisc recipe, with the exception of adding more Bailey's. As reported by the majority of others, it cracked very badly. The second I baked using all the tricks I've read about to avoid cracking. 1. All refrigerated ingredients were brought up to room temperature before mixing. 2. After baking the crust, it was put in the freezer to cool off. 3. After mixing the batter and putting it into the springform tin, the springform was placed in a waterbath, with the water being halfway up the side of the tin. I then baked the cake as written in the recipe, removing the cake from the waterbath at the end of the bake time. I put the waterbath on the shelf beneath the cake, and left everything in the oven overnight. Results: Not even so much as one crack. It was the prettiest cheesecake I've ever made, every bit as pretty as those from the gourmet shops. The recipe itself was a hit, with both cakes devoured within minutes by my colleagues. All raved about it. - 18 Jul 2008
Altered ingredient amounts.
I made this cake for my husband's birtday party and it was HEAVENLY!!! I did all the tricks GinnyG recomended, plus greasing and flouring the pan which resulted in a perfect finish but what really made it special was the topping I took from the chocolate mocha cheescake found on this site. Instead of the Tia Maria I added 2 tbsp of Baileys and I piped it on in spirals. It was by far the best cheesecake I've ever eaten, I couldn't believe I'd made it myself lol will now be my favorite go-to for company - 01 Feb 2009
Altered ingredient amounts.
3 tablespoons cocoa in the base was more than enough even though I used digestive biscuits. Also I used lower fat (medium, not lowest possible) cream cheese and it still turned out delicious. - 21 Nov 2010