Prep the pan: Line a 12-cup muffin tin with paper liners. Preheat oven to 350°F (175°C).
This ensures even baking from the start.
Whisk dry ingredients: In a medium bowl, whisk flour, cornstarch, baking powder, baking soda, and salt. Set aside.
Cream butter and sugar: In a large bowl, beat butter, sugar, and honey on medium-high until pale and fluffy, 2–3 minutes. This traps air and lightens the crumb.
Add eggs and flavor: Beat in eggs one at a time.
Mix in vanilla and lemon zest until smooth. Scrape the bowl so everything blends.
Fold in yogurt and milk: On low speed, mix in half the dry ingredients, then the yogurt, then the remaining dry ingredients along with the milk. Mix just until combined. Do not overmix.
Add fruit (optional): Toss berries with 1 tsp flour to prevent sinking.
Gently fold into batter.
Fill liners: Divide batter evenly among cups, about 3/4 full. Smooth tops lightly with a spoon.
Bake: Bake 16–20 minutes, until tops spring back and a toothpick comes out clean or with a few moist crumbs. Rotate the pan once if your oven has hot spots.
Cool: Let cupcakes cool in the pan 5 minutes, then transfer to a rack to cool completely before frosting.
Make the frosting: In a chilled bowl, beat cold heavy cream to soft peaks.
In another bowl, whisk yogurt, powdered sugar, lemon juice, and vanilla until smooth. Fold whipped cream into the yogurt mixture until fluffy and spreadable.
Frost and garnish: Swirl frosting onto cooled cupcakes. Top with fresh berries and a little lemon zest for brightness.