1- Preheat the oven to 350°F. Line an 8×8-inch baking pan with parchment paper, leaving some overhang if possible. This makes lifting the blondies out much easier once they cool.

2- Gather all ingredients and let the egg and butter come to room temperature. This helps the batters mix smoothly and keeps the texture even.

3- In a medium bowl, cream together 4 tablespoons butter and 1/4 cup granulated sugar until light and smooth.

4- Mix in 1 egg yolk, 1/4 teaspoon vanilla extract, 1/4 teaspoon almond extract, and 1/4 teaspoon orange zest if you want that light citrus note.

5- Add 2/3 cup almond flour and a pinch of salt. Stir until a smooth paste forms. Set this aside while you make the blondie batter.

6- In a separate bowl, cream together 1/2 cup softened unsalted butter and 1 cup packed light brown sugar until the mixture looks fluffy.

7- Add 1 large egg, 2 teaspoons vanilla extract, and 1/4 teaspoon almond extract. Mix until fully blended.

8- Stir in 1 and 1/3 cups all-purpose flour, 1/4 teaspoon baking powder, 1/4 teaspoon salt, and 1/3 cup almond flour. Mix just until combined. Do not overmix, or the bars may turn dense.

9- Spread the blondie batter evenly into the prepared pan. A small offset spatula helps, but the back of a spoon works too.

10- Dollop the frangipane on top in small spoonfuls, then gently swirl it through the batter with a knife. Try not to mix it in fully. You want pretty ribbons of almond filling.

11- Sprinkle 1/2 cup sliced almonds over the top so they bake into a golden, crunchy layer.

12- Bake for about 30 minutes, or until the edges are golden and the center looks set. A toothpick should come out with a few moist crumbs, not wet batter.

13- Cool the blondies completely in the pan before lifting them out. Dust with powdered sugar, then cut into 16 squares.