Heat oven to 350°F. Line an 8-inch square pan with parchment, leaving overhang.
Whisk flour, oats, both sugars, baking powder, and 1/2 tsp salt in a bowl.
Stir in melted butter and vanilla until the mixture forms moist, clumpy crumbs.
Press about two-thirds of the crumb mixture firmly into the pan to make an even base.
Toss cranberries with 2/3 cup sugar, cornstarch, orange zest, orange juice, and a pinch of salt.
Spread the cranberry filling evenly over the crust, including juices.
Crumble the remaining dough over the top, leaving some berries peeking through.
Bake 38–42 minutes, until bubbling at the edges and the topping is golden brown.
Cool completely in the pan. Chill 30 minutes for cleaner cuts, then slice into bars.
Notes
Swap the orange zest for lemon and add 1/2 cup chopped pecans to the crumble for a nutty twist. Drizzle cooled bars with a simple glaze (powdered sugar + orange juice) for extra sweetness. Store at room temperature up to 2 days, or refrigerate in an airtight container for 1 week; bars freeze well for 2 months.This recipe is an original creation inspired by classic Cranberry Crumb Bars Recipe flavors. All ingredient ratios and instructions are independently developed.