Preheat oven to 180 degrees C. Grease and flour two round cake tins. Line a tray with baking paper.
In a saucepan heat sugar and almonds over low heat until the sugar turns deep brown. Do not stir. Pour into lined tray. Allow to cool. When cool grind it in the food processor until it becomes a powder.
Cream the butter then add the sugar until fluffy. Beat in eggs one at a time. Sift in the flour, baking powder and praline and mix, adding milk to keep moist. Pour into the cake tins and bake until a toothpick inserted into the centre comes out clean, about 25 minutes. Allow to cool on a cooling rack before icing.
Boil sugar and water until sugar is dissolved then lower heat. Beat egg yolk in bowl then add to the saucepan of sugar water, stirring, about 10 minutes. Do not let it boil. In a bowl, beat butter then add in the custard mixture then stir in the vanilla and praline.