In the summer, when peaches are in season, there is practically nothing better to make than these peach crumb bars. With an easy bottom crust and top crumble, the combination is a perfect marriage with the peaches in between.
In the bowl of an electric mixer, cream the butter and sugar until light and fluffy, 3-5 minutes. Add egg yolks one at a time, mixing between each addition until incorporated. Add vanilla and mix. The dough may look curdled but that is normal.
Add the flour, baking powder, and salt. Mix until just combined and no dry streaks remain, 1-2 minutes.
Line an 8x8 baking dish with a parchment sling and butter the sides. Add half of the dough to the prepared pan and press evenly to create the bottom crust.
Spread jam on the bottom crust. Line the sliced peaches over the preserves. This usually takes three rows, and as long as the peaches are even, overlap peaches if necessary. Sprinkle with brown sugar, cinnamon, and ground ginger. Top with the remaining dough by breaking it into small pieces evenly over the peaches.
Bake in a preheated 350°F oven for 35-45 minutes. If the top seems to be getting too brown, cover with foil. The bars will become puffed and golden on the top and the edges should have a little bubbling from the preserves.
Remove from the oven and let cool completely before cutting, at least 4 hours. If not, they will not cut well. Remove parchment sling and cut into squares.