Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line a 12" x 9" traybake tin
Make the sponge by mixing the butter and light brown sugar in a large bowl, ideally using an electric mixer
Add the eggs and Baileys, and whisk until fully incorporated
Add the self raising flour, cocoa powder and baking powder and whisk in gently until you can't see any flour anymore
Fold in the chocolate chips with a spoon or spatula
Pour the batter into the lined traybake tin and bake for 30-35 minutes, or until a thin skewer inserted in the centre comes out clean. Leave to cool fully
To make the buttercream mix the butter and icing sugar together. Once it starts to come together add the Baileys and mix until smooth. Use an electric hand mixer for the best results
Smooth the buttercream onto the sponge using a palette knife, then add the truffles and sprinkles to decorate
Cut into squares to serve. Store leftovers in an airtight container in a cool place and eat within 3 days
Video
Notes
To make this recipe in a 9" square tin you will need:170g Butter, 170g light brown sugar, 3 eggs, 95ml Baileys, 125g self raising flour, 45g cocoa powder, ¼ tsp baking powder, 75g chocolate chips.150g butter, 300g icing sugar, 3 tbsp Baileys
Make sure all your ingredients (particularly the butter, Baileys and eggs) are at room temperature before you start baking.
I used a baking spread for the cake and unsalted butter for the buttercream.
You can use the original Baileys branded irish cream liqueur, or another version like Aldi's for example. You could also use Amarula.
I used dark chocolate chips in the sponge, but white or milk chocolate chips would also be super yummy!
I really recommend using light brown soft sugar if you can for the cake, but if you can't get hold of it, caster sugar will work well too.
The Baileys Truffles are usually available from shops like B&M Bargains, Quality Save or Home Bargain. They always seem to have them around Christmas time!
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales*. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons* and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.