For the Muffins

1. Preheat your oven to 375°F degrees. Place paper liners into a 12 cup muffin pan and set the pan aside.
2. In a small bowl, combine the granulated sugar and the lemon zest. Use your fingers to rub the lemon zest into the sugar for about 20 seconds.
3. In a large mixing bowl, whisk together the slightly cooled melted butter, the sugar that has been rubbed with lemon zest, the eggs, the Greek yogurt, and the vanilla extract. Whisk until everything is well combined.
4. In a separate mixing bowl, whisk together the all-purpose flour, the cake flour, the baking powder, and the salt.
5. Use a large spatula or a wooden spoon to gently mix the dry ingredients into the wet egg and sugar mixture. Stop mixing while a few streaks of flour are still visible. Do not over mix the batter.
6. In a small bowl, toss the raspberries with 2 tablespoons of the extra all-purpose flour to coat them lightly.
7. Add the floured raspberries to the muffin batter. Gently fold them in using only two or three motions to distribute them. Be careful not to over mix the batter at this stage.
8. Cover the bowl holding the batter with a clean dish towel. Let the batter rest at room temperature for 30 minutes. While the batter is resting, prepare the streusel topping.
9. Divide the muffin batter evenly among the prepared muffin liners, filling each one almost to the top. For the best results and a higher rise, only fill every other muffin cup in the pan. This allows better air circulation as they bake.
10. Generously sprinkle the cold streusel mixture over the top of each filled muffin cup.
11. Bake the muffins for 18 to 19 minutes. They are done when the tops are slightly golden brown and a toothpick inserted into the center of a muffin comes out clean or with just a few moist crumbs attached. Avoid baking them for too long or they may become dry.
12. Remove the pan of muffins from the oven. Let them cool completely on a wire rack before you add the glaze.

For the Streusel Topping

1. To make the streusel, put the all-purpose flour and granulated sugar into a medium bowl. Whisk these dry ingredients together thoroughly.
2. Add the cold, cubed butter to the bowl. Use a pastry cutter or two forks to cut the butter into the dry ingredients until the mixture looks like coarse crumbs.
3. Place the streusel mixture into the refrigerator to chill for the 30 minutes while the muffin batter is resting.

For the Glaze

1. To make the glaze, whisk together the confectioner’s sugar, the Greek yogurt, and the whole milk in a small bowl. Mix until the glaze is smooth and has a shiny appearance. The glaze should be thick enough to coat a spoon but still pourable.
2. Drizzle the glaze over the tops of the cooled muffins just before you plan to serve them.