Prep the pan and oven. Heat the oven to 375°F (190°C). Line a standard 12-cup muffin tin with paper liners or lightly grease it.
Whisk dry ingredients. In a large bowl, whisk the whole wheat flour, all-purpose flour, baking powder, baking soda, salt, and cinnamon until evenly combined.
Blend wet ingredients. In a separate bowl, whisk the eggs, maple syrup, olive oil, Greek yogurt, and vanilla until smooth. Stir in the lemon zest if using.
Combine gently. Pour the wet mixture into the dry ingredients.
Stir with a spatula until just combined. The batter should be thick and slightly lumpy. Avoid overmixing.
Fold in berries. If using frozen berries, do not thaw.
Toss berries with a teaspoon of flour to reduce bleeding, then fold them gently into the batter.
Fill the cups. Divide the batter evenly among the 12 muffin cups, filling each about 3/4 full. Sprinkle the tops with turbinado sugar for a light crunch, if you like.
Bake. Bake for 16–20 minutes, until the tops are golden and a toothpick comes out clean or with a few moist crumbs.
Cool. Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. This helps keep the bottoms from steaming and getting soggy.