Preheat your oven to 350 degrees. Spray a muffin pan with nonstick cooking or baking spray or line with paper liners.

In a medium bowl, whisk together flour, baking powder and salt. In your mixer bowl, whisk egg until light and fully combined, about 20 seconds. Add sugar and whick until thick and light yellow, about 30 seconds. Add melted butter in parts, whisking after each addition. Add sour cream and whisk until fully combined. Add zest from orange and whisk just until distributed.

Add frozen berries to dry flour mix and toss to distribute and coat. Add sour cream mixture to flour and fold gently until batter comes together and berries are distributed. Do not overmix. Small spots of flour are okay. Batter will be thick.

Use ice cream scoop or large spoon to fill muffin tin to top of each opening. Bake until light golden brown and tester comes out clean, 25-30 minutes. Rotate your pan halfway through to ensure even baking.

Cool in pan on rack at least a few minutes, then remove muffins from pan to rack and cool 5 minutes.