Preheat your oven and prepare a baking dish.
In a bowl, combine the plain flour, caster sugar, unsalted butter, and vanilla extract to form a dough.
Press the dough into the base of the prepared baking dish and bake until lightly golden.
While the base is baking, prepare the raspberry layer by mixing the softened butter and caster sugar until creamy.
Add the eggs one at a time, mixing well after each addition.
Stir in the ground almonds, plain flour, almond essence, and vanilla extract until combined.
Spread the raspberry jam over the baked base, then pour the almond mixture on top.
Sprinkle flaked almonds over the almond layer and return to the oven to bake until set and golden.
Once baked, allow to cool before preparing the icing.
Mix the icing sugar with enough water or lemon juice to achieve a drizzle consistency.
Drizzle the icing over the cooled Bakewell slice and let it set before cutting into squares.
