Combine thawed sour cherries, sugar, the juice of the lemon, lemon zest, and vanilla extract in a bowl. Toss gently and let sit while you prepare the dough. The sugar will draw out the juices, creating a syrupy base.

In the mixer bowl, whisk together flour, kosher salt, and instant yeast.

Add butter and granulated sugar to the mixer. Beat on medium speed until light and fluffy. Warm the milk slightly (no more than 110°F) and stir in  vanilla extract. Add to the butter. Add the 2 whole eggs and the extra yolk to the bowl. Beat on low speed until just combined. Do not over beat; the mixture will look slightly curdled before the flour is added.

With the mixer on low, add half of the dry flour mixture, then the remaining liquid (if any), then the rest of the flour. Mix just until a thick, elastic dough forms. Stop mixing as soon as the dough comes together; over mixing can make it tough.

Transfer the dough to a greased 9x9 inch pan, smooth the top, cover loosely with plastic wrap, and refrigerate overnight (about 8 hours) to develop flavor and texture.

Cold fermentation is optional but yields a richer flavor and better crumb.

Strain the macerated cherries, reserving the juice. Place the juice (and any released fruit) in a medium saucepan. Simmer over medium heat until reduced by half and syrupy. In a small cup, dissolve 2 tsp cornstarch in 2 tsp water, then whisk into the simmering sauce. Bring back to a boil to thicken, then remove from heat and whisk in 1 tbsp butter. Let cool slightly.

• Do not over cook the fruit; you want the cherries to stay whole.
• A slurry prevents lumps from forming.

In a bowl combine flour, brown sugar, cinnamon, and a pinch of salt. Add cold  butter cut into cubes. Using fingertips or a pastry cutter, work the butter into the dry mixture until it resembles coarse crumbs with some pea size pieces.

• Work quickly to keep butter cold for a flaky texture.
• If the mixture feels too wet, add a little more flour.

Preheat the oven

Set the oven to 350°F (177°C) and allow it to fully preheat.

Remove the dough pan from the fridge. Spoon the cherry mixture evenly over the dough surface, then sprinkle the streusel topping over the fruit.

• Distribute cherries evenly for consistent flavor in each slice.

Place the pan in the middle rack and bake for 35 minutes, or until the cake is puffed, the center is set, and the streusel is golden brown. If the top browns too quickly, cover loosely with foil halfway through.

Allow the cake to cool in the pan for 20 minutes before cutting into squares. Serve warm or at room temperature. Warm slices pair nicely with a splash of milk or coffee.