1-First Step: Preheat your oven to 350°F (175°C) and line a muffin pan with 12 cupcake liners. This sets you up for even baking.

2-Second Step: In a large bowl, whisk together 1 cup granulated sugar (200g) and zest of 1 large lemon (about 1 Tbsp or 5g) until fragrant. Add 1 1/4 cups all-purpose flour (150g), 1 1/2 tsp baking powder (6g), and 1/2 tsp fine salt (3g). Whisk to combine and set aside the dry mix.

3-Third Step: In another bowl, whisk 1/2 cup full-fat sour cream (125g), 1/2 cup water (120g), 1/4 cup vegetable oil (56g), 1 large egg (56g), and 1 tsp vanilla extract (4g) until smooth. Pour wet into dry ingredients and whisk just until mixed. Avoid overmixing for tender results.

4-Fourth Step: Use a cookie scoop to fill liners 3/4 full. Bake 19-21 minutes until a toothpick comes out with moist crumbs. Cool 10 minutes in pan, then transfer to a rack. For gluten-free, let batter sit 30 minutes first.

5-Fifth Step: Beat 1 cup unsalted butter (226g) for 30 seconds until smooth. Add zest of 1 large lemon (1 Tbsp), 1 tsp vanilla (4g), 1 tsp lemon extract (4g), and 1/4 tsp salt (1g). Beat on low.

6-Sixth Step: Mix in 3 Tbsp seedless strawberry jam (60g). Gradually add 3 1/2 cups powdered sugar (454g) and 1 Tbsp heavy cream (15g) on low, scraping the bowl. Add optional red gel food coloring for pink. Stir by hand for silky texture. Adjust with cream or sugar. Halve if you prefer smaller swirls.

7-Seventh Step: Optional: Coat a piping bag with 1 Tbsp strawberry jam inside for marbled effect, then fill with buttercream and attach large round piping tip.

8-Eighth Step: Once cupcakes cool fully, core centers with a knife or 3/4-inch cutter. Fill each with 1 Tbsp strawberry jam (from 3/4 cup total).

9-Final Step: Pipe a generous swirl of buttercream on top. Garnish with thin lemon slices and heart-shaped strawberry pieces from 6 small strawberries. Serve at room temp for best flavor. These strawberry cupcakes shine at parties!