Bright, chewy lemon blondies studded with juicy blueberries and a hint of vanilla. Simple pantry ingredients, no mixer required, and ready in about 40 minutes.
Preheat oven to 350°F. Line an 8 by 8 inch metal baking pan with parchment, leaving overhang, and lightly grease.
In a small bowl, gently toss blueberries with cornstarch to coat; set aside.
In a large bowl, whisk melted butter, granulated sugar, and brown sugar until glossy and well combined.
Whisk in eggs, vanilla, lemon zest, and lemon juice until smooth.
Add flour, baking powder, and salt. Fold with a spatula just until no dry streaks remain.
Fold in coated blueberries and white chocolate chips (if using), taking care not to burst the berries.
Spread batter evenly in the prepared pan. Smooth the top.
Bake 23 to 27 minutes, until the edges are set and a toothpick inserted in the center comes out with a few moist crumbs.
Cool in the pan on a rack for 30 minutes. Use parchment to lift out, then cut into 16 bars and serve.
Notes
For extra lemon pop, drizzle with a quick glaze (0.75 cup powdered sugar whisked with 1.5 tbsp lemon juice) after cooling. Store airtight at room temperature up to 2 days or refrigerate up to 5 days.