Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking dish.

Hull and slice strawberries into 1/4-inch rounds and slice rhubarb into thin pieces. Zest a lemon and set aside.

In a large mixing bowl, combine melted butter, brown sugar, and granulated sugar, stirring until smooth. Add eggs one at a time, mixing well after each addition, then stir in vanilla extract and lemon zest.

In a separate bowl, whisk together flour, baking powder, and salt.

Gradually add dry ingredients to wet mixture, stirring until just combined.

Gently fold in three-quarters of the strawberries and rhubarb into the batter.

Pour the batter into the greased baking dish and spread evenly.

Top with remaining strawberry slices and rhubarb pieces, then sprinkle with white chocolate chips.

Bake for 30-35 minutes until golden brown and a toothpick comes out with moist crumbs.

Cool in the pan for at least 15 minutes before serving.