Step 1

Preheat the oven to 350 degrees F (180 C). Prepare a 12-count muffin pan with paper liners and set aside.

Step 2

In a medium bowl, combine flour, baking powder, and salt. Whisk to combine and set aside.

Step 3

Using a handheld or stand mixer fitted with the paddle attachment, beat the butter and sugar together on medium-high speed until creamed, 2-3 minutes. Add the eggs and vanilla, scrape down the sides of the bowl, and beat again on medium-high speed until mixture is well-combined.

Step 4

Add the dry ingredients to the butter-sugar mixture in three batches, beating on low speed after each addition. Mix in the milk, lemon zest, and juice, and beat again on low speed just until combined. Do not overmix.

Step 5

Divide batter evenly between 12 cupcake liners, and bake for 18-20 minutes, until a toothpick inserted in the middle of cupcakes comes out clean. Remove from the oven, allow to cool in the pan for 10-15 minutes, then remove to a wire rack to cool completely before filling and frosting.

Step 6

To fill the cupcakes, use a small paring knife to cut a small cone out of the center of each cupcake, making a well about 1-1 1/2 inches deep. Spoon a small amount of lemon curd into the well. If you like, you can slice each cone you removed and replace just the top edge, so the top of the cupcake still has a smooth surface of cake with the curd underneath. (This is definitely not necessary, but is pretty quick and easy and can make the cupcakes slightly easier to frost.)

Step 7

To make the frosting, using a handheld or stand mixer with the paddle attachment, beat the cream cheese and butter on medium-high for 2-3 minutes, until light and fluffy. Add in the powdered sugar and mix on low speed just until incorporated, then increase the speed to medium-high and beat 3-4 minutes, until mixture is smooth and light. Add the vanilla and poppy seeds, and beat again 1-2 minutes. Frost cupcakes as desired.