Preheat the oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the long sides for easy removal. Lightly spray the parchment and exposed sides of the pan with nonstick cooking spray.
nonstick cooking spray, parchment paper
In a large mixing bowl, beat the softened butter, granulated sugar, and light brown sugar together until light and fluffy, about 2–3 minutes with a hand mixer on medium speed. If mixing by hand, use a sturdy wooden spoon and mix until well combined and slightly creamy.
1 cup unsalted butter, 1 cup granulated sugar, 1/2 cup light brown sugar
Beat in the eggs one at a time until fully incorporated. Add the vanilla extract and almond extract and mix until smooth and slightly thick.
2 large eggs, 2 teaspoons pure vanilla extract, 1 teaspoon almond extract
In a separate bowl, whisk together the flour, baking powder, and salt until well blended.
2 1/2 cups all-purpose flour, 1 teaspoon baking powder, 1/2 teaspoon fine sea salt
Add the dry ingredients to the butter mixture in two additions, mixing on low speed or by hand just until combined after each addition. The dough should be thick and slightly sticky, similar to a soft cookie dough.
2 1/2 cups all-purpose flour, 1 teaspoon baking powder, 1/2 teaspoon fine sea salt
Transfer about 2/3 of the dough to the prepared pan, leaving the remaining 1/3 in the bowl for the crumb topping. Press the dough evenly into the bottom of the pan, making sure to press it into the corners for a uniform base.
Bake the crust for 10 minutes. It will not look fully baked yet; it should appear slightly puffed but still pale. Remove from the oven and leave the oven on.
While the crust par-bakes, gently stir the cherry pie filling in a bowl to loosen it, or stir the cherry jam/preserves until spreadable. If using, fold in the finely chopped maraschino cherries.
1 can cherry pie filling, 1 1/2 cups cherry jam or cherry preserves, 1/4 cup maraschino cherries
Spread the cherry pie filling OR cherry jam evenly over the hot par-baked crust, all the way to the edges, creating an even layer so each bar gets plenty of cherry.
1 can cherry pie filling, 1 1/2 cups cherry jam or cherry preserves
Break the remaining dough into small clumps with your fingers and scatter them evenly over the cherry layer, allowing some of the cherries to peek through. Sprinkle the sliced almonds evenly over the top.
1/2 cup sliced almonds
Return the pan to the oven and bake for 25–30 minutes, or until the top is lightly golden and the edges are set. The center should look just set and not jiggly. Start checking around 23–24 minutes, as ovens vary.
Place the pan on a wire rack and let the bars cool completely for at least 2 hours. This allows the cherry layer to firm up so the bars slice cleanly.
If desired, melt the white chocolate chips in a microwave-safe bowl in 15-second bursts, stirring between each, until smooth. Drizzle the melted white chocolate over the cooled bars and let it set.
1/2 cup white chocolate chips
Use the parchment overhang to lift the cooled slab out of the pan. Place on a cutting board and slice into 18 larger bars or up to 24 smaller squares, wiping the knife between cuts for the neatest edges. Serve at room temperature.