1-Make lemon curd ahead, because it takes: Make lemon curd ahead, because it takes time to cool and set completely. I recommend cooking the lemon curd in a double boiler because mixing these ingredients over direct heat quickly leads to burning. Whisk together egg yolks, granulated sugar, lemon zest and lemon juice into the top pot of your double boiler, place over simmering water and then using a silicone spatula continue to stir as the curd cooks. Stir constantly to prevent the egg yolks from curdling. Cook until the mixture becomes thick, about 10 minutes. If curd isn’t thickening, turn up the heat and constantly whisk.
2-Remove pan from heat, add butter and: Remove pan from heat, add butter and whisk into the curd. The butter will melt from the heat of the curd. Pour curd into a jar or bowl and place a piece of plastic wrap directly on top so it is touching the top of the curd to prevents a skin from forming on top. The curd will continue to thicken as it cools.
3-Preheat oven to 350F: Preheat oven to 350F. Line a 12-count muffin pan with paper liners and set aside.
4-Stir together flour, baking powder, baking soda,: Stir together flour, baking powder, baking soda, and salt, set aside.
5-Beat the butter on high speed until: Beat the butter on high speed until smooth and creamy (about 1 minute), then add sugar and cream together. Add eggs, vanilla extract, lemon zest and Greek yogurt, and mix just to combine. Add lemon juice and mix to combine.
6-Finally, add flour mixture and mix until: Finally, add flour mixture and mix until combined.
7-Spoon batter into prepared pan, filling them: Spoon batter into prepared pan, filling them about ½ full with muffin batter.
8-Drop about a tablespoon of lemon curd: Drop about a tablespoon of lemon curd into the center of each muffin, cover with a thin layer of muffin batter. The cups should be about ¾ full. Then generously top with streusel crumb. Gently press the crumb to stick to the batter.
9-Bake for about 25 minutes or until: Bake for about 25 minutes or until the muffin has set and the crumbs get nice golden brown color.
10-To make the glaze, stir together powdered: To make the glaze, stir together powdered sugar and milk (or creme) and drizzle over the muffins. If the glaze is too thin add more liquid, if it is too thin add more powdered sugar