Preheat oven to 425 degrees Fahrenheit. Line two muffin pans with 18 paper liners.
In a large bowl, whisk to combine the flour, cocoa powder, sugars, baking powder, baking soda and salt. Set aside.
In a medium bowl, whisk to combine the butter, eggs, sour cream, buttermilk, vanilla extract and lemon zest until just combined.
In a small bowl, toss the raspberries with the tablespoon of flour. This will keep the raspberries from sinking in the batter while they bake.
Pour the wet ingredients into the dry ingredients. Stir with a spatula until almost combined. Stop stirring when you see just a few streaks of flour remaining. They will get mixed when you add the berries. Add 1 cup of the raspberries and gently fold them in. Be careful not to overmix the batter.
Transfer batter to your prepared muffin tin (an ice cream scoop works well for neatly and evenly scooping batter into the muffin tin). Fill each one to the top with batter. Leaving a space between each muffin will help muffins rise higher but it's not necessary. Sprinkle turbinado sugar evenly on top of every muffin and gently press a raspberry or two on top.
Bake at 425 for 6 minutes. Reduce heat to 350 Fahrenheit and bake an additional 9-11 minutes. Check for doneness with a toothpick. When a toothpick comes out clean when inserted in the center of a muffin, they are done. Remove from oven and allow muffins to cool in the pan for 10 minutes then transfer muffins to a wire rack to cool completely.