Step 2. Forget until morning.
Step 3. Decide only a brownie cheesecake will do.
Step 4. Find multiple recipes, all of which require multiple stages of baking, multiple hours cooling time, or multiple ingredients not currently in the house.
Step 5. Find some promising, nearly there, recipes, combine, increase, simplify, and come up with this.
Melt 4 oz plain chocolate with 5 oz butter over a very very low heat. Dump a teaspoon of vanilla essence and 8 oz sugar into the saucepan, stir. Add 2 eggs, 2 oz plain flour and a goodly sprinkle of salt, stir until smooth.
Pour into bottom of a greased ten inch loose bottom cake tin. Chill in fridge (or freezer, if you're a fast worker) whilst making the cheesecake layer.
Preheat oven to 160C.
Take 450g cream cheese, 2 eggs, a gloom of vanilla bean paste, and a big dollop Greek yoghurt (in this case, fat free Greek yoghurt, and half full fat, half low fat cream cheese as that's what I had. I might have gone for sour cream over yoghurt if I'd had the choice). Whisk until smooth.
Pour very gently over brownie base, then bake at 160C until it looks about right. 57 minutes in this case. Turn off oven, leave cheesecake in to cool. Panic slightly about time, remove before totally cold and put in garden to finish chilling.