Prep your tools. Line a 9×13 baking dish with tin foil, being sure to leave an overhang so that you can easily lift everything out of the pan after baking.

Combine the dry ingredients. In a food processor, pulse the walnuts until they are finely ground. Add the flour, confectioners sugar, baking powder, and salt. Pulse to combine. Add the butter and pulse until the mixture resembles coarse breadcrumbs.

Mix wet ingredients. In a medium bowl, combine the egg, egg yolk, and vanilla extract. Whisk briefly with a fork to combine.

Add wet to dry ingredients. Turn your food processor on and add the egg mixture with it running. Turn off the food processor and then pulse the mixture until clumps form.

Chill. Press the cookie dough into the bottom of your prepared 9×13 baking dish. Use your hands to spread the cookie dough over the bottom of the dish. Chill in the fridge until the dough is firm, about 30 minutes.

Preheat your oven to 350F. When the dough has chilled, gently prick it all over with a fork.

Bake. Place the baking dish in the oven and bake until the edges are golden, about 25 minutes. Set aside to cool. Don’t turn your oven off.

Add toppings. Spread the blueberry jam all over the top of the cooled cookie base. Sprinkle the granola on top of the jam, gently pressing it down into the jam so that the granola sticks to it.

Bake again. Place the baking dish back in the oven and bake a second time until the jam is bubbly, about 30 minutes. Set aside to cool.

Lift and cut. Use the tin foil overhang to gently lift everything out of the baking dish and transfer it to a flat surface. (I recommend doing this right next to your cutting board or counter so that you don’t have to move it all too far.) With a sharp knife, cut into cookie bar squares.