- Preheat your oven to 180C/350F and line a cake tin with greaseproof paper. 
- Place the sugar, flour, ground almonds, baking powder and salt into a bowl. 
- Add the butter and beat on low until the mixture has a wet sand appearance and no butter portions remain that are larger than a pea (the smaller the better), approximately 2 minutes. 
- Pour the milk, buttermilk and almond extract into a small jug and stir together until smooth, pour into the dry ingredients and combine on low until no dry portions remain in the bowl. 
- Scrape down the sides of the bowl and add in one egg and beat on low until it is fully combined, approximately 40 seconds. 
- Repeat with the remaining egg and beat until combined. 
- Pour half into the cake tin and spread out evenly. 
- Spoon the almond frangipane mixture over the cake and spread out. 
- Pour the remaining batter over the top of the frangipane and smooth out. 
- Sprinkle over the sliced almonds and bake until golden, approximately 35 minutes or until a skewer comes out clean. 
- Remove and allow to cool in the tin for 5 minutes before turning upside down onto a cooling rack. 
- Set aside to cool completely. 
- Sprinkle over a little powdered sugar. 
- Slice up and serve!