Preheat the oven to 350 degrees F. Line two cupcake pans (24 cupcakes) with cupcake liners and set aside.
Chop the frozen raspberries, enough to measure 1 cup for the cake batter, and set aside while you mix the cake batter.
In a medium-sized mixing bowl, add the flour, baking powder, baking soda and salt and whisk well, then set aside.
In another medium-sized bowl, add the sour cream, milk, vanilla extract and lemon zest. Whisk well and set aside.
In a large mixing bowl, add the room-temperature butter and the sugar and mix on medium-high speed with an electric mixer for a couple minutes until light and fluffy.
Add the eggs, one at a time mixing for about 20 seconds after each egg.
Alternately add in the dry mixture and the liquid mixture to the butter/egg mixture, starting and ending with the dry mixture.
(Add in ⅓ of the dry mixture and mix on medium speed just until combined. Add in ½ the liquid mixture, mixing on medium speed only until combined. Add in another ⅓ of the dry mixture, mixing on medium speed only until combined. Add in the last of the liquid mixture, mixing on medium speed only until combined, then the last of the dry mixture and mix until combined.)
Be very careful only to mix until well combined. Mixing too long and at too high of a speed can cause the cupcakes to come out dense and rubbery.
The batter will be thick at this point.
Before adding the raspberries, add about 1 heaping tablespoon of plain cupcake batter to each cupcake liner and spread around the bottom of the liner.
Add the chopped raspberries to the remaining batter in the mixing bowl and fold in with a large spoon or silicone spatula.
Add the rest of the batter to the cupcake liners. (Doing it this way will help keep the raspberries from sinking all the way to the bottom.) In my opinion, this works better than coating fruit with flour, but use the method you prefer.
Bake in the preheated oven at 350 degrees F for 15-18 minutes. Ovens vary, so watch the cupcakes closely starting at about 15 minutes. Cupcakes are done with they're puffed up slighty, lightly golden on the edges and a toothpick into one of the middle of a couple of cupcakes comes out with either a few moist crumbs on it or clean. Be very careful not to bake too long or the cupcakes could dry out.
Place the cupcake pans on cooling racks and let cool in the pans for about 7 minutes, then remove the cupcakes from the pans and let them cool on the wire racks until completely cooled. The tops of the cupcakes may flatten out as they cool. That’s normal for these cupcakes.
Mix the frosting according to the directions below and add the frosting to the cooled cupcakes.
See the notes section for best ways to store these cupcakes, how to serve them and for more questions.