1-First Step: Prep the pan and oven Start by preheating your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper, leaving enough overhang on two sides so you can lift the bars out later. This makes slicing much easier and helps prevent sticking. If you are using a glass pan, keep in mind that it may need 3 to 5 extra minutes in the oven. That small adjustment helps the center bake through without overbrowning the edges.

2-Second Step: Make the frangipane In a medium bowl, cream 1/4 cup softened butter with 1/4 cup granulated sugar until smooth and fluffy. Mix in 1 large egg yolk, 1/2 tsp vanilla extract, 1/2 tsp almond extract, and the optional zest of 1/2 orange if you want a brighter flavor. Stir in 1/2 cup almond flour and a pinch of salt until a thick paste forms. The mixture should look spreadable but still hold its shape when spooned. Set it aside while you make the blondie batter.

3-Third Step: Mix the blondie batter In a large bowl, beat 1/2 cup softened butter with 1 cup packed light brown sugar until combined and creamy. Add 1 large egg, 1 tsp vanilla extract, and 1/2 tsp almond extract, then mix until smooth. Gently fold in 1 cup all-purpose flour, 1/4 cup almond flour, 1/2 tsp baking powder, and 1/4 tsp kosher or sea salt. Stop mixing as soon as you no longer see dry streaks. This is the part where you want to be careful, because overmixing can make the blondies dense instead of soft and chewy.

4-Fourth Step: Assemble the layers Spread the blondie batter evenly into the prepared pan. It will be thick, so use a spatula to nudge it into the corners. Next, dollop the frangipane over the top in small spoonfuls. Use a spatula or skewer to swirl gently through the batter. You are looking for a marbled look, not full blending. Then sprinkle 1/2 cup sliced almonds over the surface so they toast as the bars bake.

5-Fifth Step: Bake until set Bake for 28 to 32 minutes, until the edges are golden and set and the center feels slightly firm. A toothpick inserted in the middle should come out with moist crumbs, not wet batter. If you like a gooier center, check on the earlier side of the range. Let the blondies cool completely in the pan on a wire rack. Cooling is important because the bars continue to set as they rest. If you cut too early, they may crumble or lose their clean edges.

6-Final Step: Slice and serve Once fully cooled, use the parchment overhang to lift the whole slab out of the pan. Dust with powdered sugar if you want that bakery look, then slice into 16 squares. Serve them as an afternoon snack, a brunch treat, or a simple dessert with coffee or tea.