Preheat the oven to 425F. Grease a 12 count standard size muffin tin or line with parchment liners and set it aside. For these muffins, I definitely recommend the parchment liners, because these like to stick to the muffin tin.
In a medium bowl, whisk together the flour, poppy seeds, baking powder, baking soda and salt. Set this aside.
In a large bowl, use a hand mixer or a stand mixer fitted with a paddle attachment to beat the butter on high speed until it is smooth and creamy, about a minute. Then add the sugar and beat on high speed until they are fully creamed together, about 2 minutes. Add the eggs, sour cream and vanilla extract and beat until combined.
Add the dry ingredients to the wet and beat on low speed until just barely combined. Then add the lemon zest, lemon juice and milk and beat on low speed until just combined.
Pour out the batter into the prepared muffin tins, filling them all the way to the top. Bake at 425F for 5 minutes, then keep the muffins in the oven, but lower the temperature to 350F for 13-15 additional minutes, or until a toothpick inserted into the centers comes out clean. Allow them to cool in the pan for 10 or so minutes, then remove them to a wire rack to cool completely.
Store in an airtight container for 3-4 days and enjoy!
