Mazurka with Almonds

Preheat the oven to 350°F (175°C). Grease a 9-inch round or rectangular baking pan with butter and set aside.

Cream together the 400 g butter and confectioner's sugar in a large bowl, beating until light and fluffy, approximately 3-4 minutes.

Add the eggs one at a time to the butter mixture, beating well after each addition to fully incorporate.

Stir in the vanilla extract until evenly distributed throughout the batter.

Fold in the ground almonds and flour gently using a spatula, mixing until just combined and no dry flour remains visible.

Pour the batter into the prepared baking pan and smooth the top with a spatula to ensure even thickness.

Bake in the preheated oven for 30-35 minutes, until the cake is golden brown and a toothpick inserted in the center comes out clean.

Remove from the oven and allow the mazurka to cool in the pan for 10 minutes before turning out onto a wire rack to cool completely.