Place the flour, baking powder, salt, 1/2 cup sugar, egg, egg yolk, butter, and lavender in a mixing bowl. Use the dough hook of your mixer or your hands to knead the mixture into streusel.

Preheat the oven to 350 degrees F. Line a 10-inch baking pan with parchment paper.

Separate 2/3 of the dough and press it into the prepared baking pan, forming an edge 1/2 inch up the side of the pan.

Puncture the dough on the bottom of the pan several times with a fork.

Cover with a layer of baking paper and distribute pie weights on top.*

Place in the oven and bake for 10 minutes.

Rinse cherries, drain and remove the stems and pits.

Remove the pie weights from the pan. Spread the cherries out on the pre-baked dough base.

Sprinkle vanilla extract and 2 tablespoons of sugar over the cherries.

Spread the remaining streusel evenly over the cherries.

Bake in the oven for 30 minutes.

Remove from the oven. Sprinkle additional dried lavender flowers over the top,

Let sit 10 minutes, then remove from the pan.

Transfer to wire rack. Let cool completely before transferring to a serving plate.

Slice and serve.