Preheat your oven to 375°F (190°C) and line an 8x8-inch baking dish with parchment paper.

Combine pitted and sliced fresh cherries with lemon juice and cornstarch in a bowl and toss until coated.

In a large bowl, mix melted butter and sugar, then add salt, baking powder, baking soda, and flour until crumbly.

Press the crust mixture into the bottom of the baking dish evenly, about 1/4 inch thick, and bake for 10 minutes.

Spread the cherry mixture evenly over the baked crust.

Sprinkle the reserved crumb mixture over the cherry filling.

Bake for an additional 25 minutes until golden brown and bubbly.

Allow to cool for 10 minutes, then sprinkle with extra sugar and slice into squares.