Preheat your oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper.

Melt the unsalted butter in a medium saucepan over low heat, then allow to cool slightly.

Whisk together the melted butter and light brown sugar until smooth and fully combined.

Incorporate the eggs one at a time, then blend in the vanilla and almond extracts until glossy.

Whisk together the all-purpose flour, baking powder, and salt, then gently fold this into the wet ingredients.

For the frangipane filling, combine almond flour and granulated sugar, add an egg and stir until smooth.

Spread the blondie batter in the prepared pan, dollop frangipane on top, and swirl together.

Sprinkle sliced almonds on top and bake for 30-35 minutes until golden brown and a toothpick comes out with a few moist crumbs.

Let cool completely in the pan, slice into squares and serve.