Preheat oven to 425° F. Spray a 12-count muffin pan with nonstick spray or line with cupcake liners.
Make the muffins: Using a handheld or stand mixer fitted with a paddle attachment, beat the butter and both sugar together on high speed until smooth and creamy, about 2 minutes. Scrape down the sides and bottom of the bowl as needed. Add the eggs, yogurt, vanilla extract, lemon extract and lemon zest. Beat on medium speed for 1 minute, then turn up to high speed until the mixture is combined. Scrape down the sides and bottom of the bowl as needed.
Whisk the Premier Protein Vanilla Milkshake Powder, flour, baking soda, baking powder and salt together in a medium bowl. Pour the dry ingredients into the wet ingredients, and 1/4 cup of milk, and mix one low speed until everything is combined. If mixture is too dry, add more milk 1 tbsp at a time. Gently fold in the poppyseeds.
Spoon the batter evenly into each cup or liner, filling each almost all the way to the top.
Bake for 5 minutes at 425° F, then keeping the muffins in the oven, lower the oven temperature to 350° F and bake for 12-15 more minutes or until a toothpick inserted in the center comes out clean.
Muffins stay fresh store at room temperature for a few days - then transfer to the fridge for up to 1 week.