Preheat the oven 160C Fan/325F, grease a 23cm cake tin with butter then dust with a coating of flour and line with base with parchment paper.
Melt the butter the in a saucepan, add the milk and lemon juice and set to one side to cool slightly.
Whisk the eggs, sugar in a free standing mixer or electric whisk until pale, thick and creamy, this will take a good 5 minutes. Sift the flour with the baking powder and zest the lemon over the top of the flour. Carefully fold a third of the flour into the egg with a metal spoon or a spatular, trying not to knock any of the air out of the egg mixture, next fold in half of the butter mixture, then another third of the flour, then finally the rest of the butter and flour. Be very gentle to conserve as much volume as possible.
Carefully pour the batter into the prepared cake tin and bake in the centre of the oven for 25 minutes.
Now prepare the almond caramel. Place the butter in a saucepan and melt, add the flour and stir. Now add the sugars, cream salt and almonds, stir and simmer gently for a minute or two until it thickens slightly. Set to one side (this must be hot to pour over the cake) Once the cake has been in the oven for 25 minutes, gently spoon the almond caramel over the top of the cake and return to the oven. Increase the oven temperature to 185C and bake for a further 10-12 minutes.
Remove from the oven and cool in the tin for 30 minutes before turning out onto a plate. Serve with yogurt or cream.