Step 1

Preheat the oven to 350°F / 175°C and place 12 cupcake liners in a muffin pan. Set aside.

Step 2

Add 1 cup sugar and 1 Tbsp lemon zest into a large bowl. Use your fingertips to massage the zest into the sugar to help release the oil in the zest. You should be able to smell the oils being incorporated into the sugar. Set aside.

Step 3

In a large bowl, whisk together 1/2 cup sour cream, 1/2 cup water, 1/4 cup oil, 1 large egg, 1 tsp lemon extract, and 1 tsp vanilla extract. Mix until fully incorporated.

Step 4

Whisk 1 1/4 cups all-purpose flour, the lemon sugar we made in step 2, 1 Tbsp poppy seeds, 1 1/2 tsp baking powder, and 1/2 tsp salt into the wet ingredients. Mix until just combined. The batter should be smooth.

Step 5

Fill the cupcake liners 3/4 full and bake for 18-21 minutes or until a toothpick comes out with a few moist crumbs. Rotate the pan halfway through to help the cupcakes bake evenly.

Step 6

Let the cupcakes cool for 10 minutes in the pan before moving them to a cooling rack to finish cooling.

Step 7

Beat 1/4 cup of unsalted butter and 1/4 cup of cream cheese on a medium speed for 30 seconds with a hand mixer until smooth.

Step 8

Add in 1 Tbsp lemon zest, 1/2 tsp vanilla extract, and 1/4 tsp salt. Beat on low until the ingredients are combined.

Step 9

Gradually mix in 2 cups of powdered sugar and 1 Tbsp of fresh lemon juice on a low speed. Scrape the sides and bottom of the bowl with a rubber spatula as needed.

Step 10

If the frosting seems too thick, add in additional lemon juice (1 tsp at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).

Step 11

Mix on a low speed for a few minutes to make the frosting super smooth.

Step 12

Place the buttercream in a piping bag fitted with a large round frosting tip or cut a 1-inch opening at the bottom of the bag. Set aside.

Step 13

If you chose to fill these cupcakes, remove the centers with a small sharp knife or a 3/4-inch circle cutter. Fill each cupcake with 1 Tbsp of lemon curd.

Step 14

Next, make the heart garnish. Use a vegetable peeler to peel a few thin strips of skin from a lemon. Then use a small heart shaped cutter to cut out 12 little hearts. If you don't have a heart shaped cutter you can also cut them out using a sharp, small knife.

Step 15

Then pipe a large dollop of lemon cream cheese buttercream on top of each cupcake. Gently press a lemon peel heart onto each cupcake.

Step 16

Use a microplane to top the cupcakes with lemon zest and add a sprinkle of poppy seeds, then enjoy!