How to make it:
Preheat oven to 350°F. Line an 8x8 or 9x9 pan with parchment paper.

In a bowl, mix sugars, flour, salt, baking powder, and melted butter until fully incorporated; moist but crumbly.

Press about 2/3 of the crumble mixture firmly and evenly into the bottom of the pan, ensuring the corners are filled as well.

Bake crust for 5-7 minutes until lightly set.

While it bakes, beat together cream cheese, mascarpone, powdered sugar, lemon juice, and vanilla until smooth.

Toss berries with cornstarch and sugar. (If using frozen berries, do not thaw first.)

Spread cheesecake mixture over the warm crust. Scatter berries evenly on top.

Sprinkle remaining crumble over the berries.

Bake 35–40 minutes until edges are golden and center is mostly set.

Cool completely at room temp for 30 minutes, then refrigerate at least 2 hours before slicing.

A Few Notes:

• Fresh berries give a prettier texture and cleaner slices.

• Frozen berries make the bars softer and a little juicier — still delicious.

• You can make them a day in advance and keep them refrigerated until ready to serve.

• Store the bars covered in the refrigerator for up to 5 days.

• To freeze, store them in an airtight container in the freezer for up to 2 months. Thaw overnight in the refrigerator before serving.