Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.

In a large bowl, whisk together the flour, sugar, baking powder, and salt.

In another bowl, mix melted butter, eggs, milk, orange juice, and zest until combined.

Pour the wet ingredients into the dry ingredients and gently fold until just mixed—do not overmix.

Spoon the batter into the muffin tins about two-thirds full.

Bake for 18–20 minutes or until golden brown and a toothpick inserted comes out clean.