Preheat oven to 375 degrees F (190 degrees C). Grease a 9×13 inch glass baking dish.

To make the crust, whisk together the flour and powdered sugar. Cut in the cold, cubed butter with a pastry cutter, the whisk attachment on your KitchenAid, or crumble with your fingers. Press into the bottom of the glass baking dish. Bake in the preheated oven for about 20 minutes, or until the edges are golden brown.

While the crust is baking, toss the nectarines with the 1 tbsp of sugar. Melt the 1 tbsp of butter in a skillet over medium heat. Add the nectarines and toss them around to coat. Let them cook in a single layer for about 3-5 minutes, or until golden spots appear. Flip and let cook for another 3 minutes, until slightly golden. Set aside.

Whisk together the eggs, sugar, and lemon juice. Add the flour a little at a time and whisk until no longer clumpy.

Pour the batter over the hot, prepared crust. Arrange the nectarine slices in the batter. Bake for an additional 20-25 minutes, or until center is no longer jiggly.

Refrigerate for at least two hours, or until chilled. Sprinkle with powdered sugar and serve!