Preheat your oven to 350°F and line a 8x8 inch baking pan with parchment paper.
Cream the butter and white sugar together.
Mix in the egg yolk, orange zest, vanilla extract, and almond extract together.
Fold in salt and almond flour until a paste forms. Set aside.
In a large bowl, mix the softened butter and brown sugar until well combined.
Add the egg and almond extract, and mix until smooth.
Add the flour, baking powder, salt, and almond flour and stir until just combined. Do not over-mix.
Spread the batter evenly into the prepared baking pan. Top with the frangipane then swirl using a wooden skewer. Top with the sliced almonds.
Bake for 30 minutes, or until the edges are set and the center is slightly firm.
Allow the blondies to cool in the pan before dusting with powdered sugar and slicing into squares.
