Foolproof biscuit recipe that won't spread...

[FurryTurnipHead]

Hello, I'm trying to make some festive biscuits with the coloured 'windows' in made from crushed boiled sweets. Have tried 2 different recipes, both shortbread, but both have spread so much in the oven you can't see the middle at all. And the Christmas tree shape is now a massive blob.

Anyone got a foolproof recipe for something that will hold in the shape I've cut it?

Thanks!

2, 4, 6 oz of sugar, butter and plain flour respectively. Adding spices or cocoa as you wish. Beat together to form a dough. 180 C for 10 to 15 mins, depending on size of biscuits. Pretty foolproof, good luck 😊