Lemon almond slice

Ingredients

• 250 g butter, softened, chopped
• 2 tsp vanilla extract
• 1 1/4 cups caster sugar
• 1/3 cup ground almonds
• 2 cups plain flour
• 1/2 cup flaked almonds
• sifted icing sugar (optional)
• Lemon filling
• 1 tsp finely grated lemon zest
• 2/3 cup strained lemon juice
• 1 2/3 cups caster sugar
• 250 g unsalted butter, chopped
• 4 eggs, lightly beaten, strained