This delicious summer dessert is the best of all fruit desserts. It's got a sturdy crust to hold all the juicy summer fruit, a surprise almond cream as a base hiding below that fruit, and a oat crumble on top to give it the perfect crunch. A satisfying pie-crumble-galette combo that will both impress and delight your family and friends.
Add ice water a little at a time and pulse until mixture forms a dough that can holds together when you pinch a bit in your hand. Turn the dough out onto a lightly floured board. Gather dough and press into a disc.
Place disc in between two sheets of parchment paper and roll into a rough circle, about 11 inches in diameter. Place the parchment lined dough on a baking sheet and place in the freezer while you prepare the crumble and almond cream, about 30 minutes.
Blend almond paste, brown sugar, and sour cream in a food processor. You can also use a hand mixer, but is harder to get the almond paste to blend in completely. Set aside.
Add all ingredients, except the butter, to a small bowl and combine. Add small pieces of butter and using clean hands, or a fork, work the butter and mixture together until a crumble mixture appears. Chunks of butter coated with flour and oats is what you're looking for. Set aside.
Combine the egg, cream or milk, and salt and whisk until mixture is homogeneous. Set aside.
Preheat oven to 400°. Pull dough out of the freezer and peel the top layer of parchment off. Leave the bottom layer on the baking sheet and let sit out on the counter for a few minutes until it can be easily folded.
Evenly spread almond mixture over the dough, leaving a 2-inch border. Place peaches in a circle or evenly scattered around, followed by the blueberries. Sprinkle the crumble on top of the fruit. Fold the dough edge over the fruit, pleating naturally occurs as you fold. Brush the edge with egg wash and sprinkle with turbinado sugar.
Bake until crust is golden, about 35 minutes. Let cool for about 10 minutes before slicing into wedges. A scoop of ice cream on top is a very good idea.