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1
Preheat oven to 350F.
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2
Brush standard muffin tins with butter; dust with flour, tapping out excess.
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3
Whisk together flour, baking soda, baking powder, and salt.
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4
With an electric mixer on medium speed, whisk egg whites until soft peaks form.
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5
Add 1/2 cup granulated sugar; whisk until peaks are stiff and glossy but not dry (do not overbeat).
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6
Transfer mixture to a large bowl.
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7
In another bowl, with an electric mixer on medium-high speed, cream butter until smooth.
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8
Add remaining 3/4 cup granulated sugar and the zest; beat until pale and fluffy.
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9
Add yolks, one at a time, beating until each is incorporated, scraping down sides of bowl as needed.
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10
Mix in lemon juice and vanilla.
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11
Reduce speed to low.
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12
Add flour mixture in three batches, alternating with two additions of yogurt, and beating until just combined after each.
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13
Whisk one third of the egg-white mixture into batter to lighten, then gently fold in remaining whites.
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14
Divide batter evenly among prepared cups, filling each three-quarters full.
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15
Bake, rotating tins halfway through, until a cake tester inserted in centers comes out clean, about 20 minutes.
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16
Transfer tins to wire racks to cool completely before removing cupcakes.
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17
To finish, use a serrated knife (and a gentle sawing motion) to slice each cupcake twice horizontally to make three even layers.
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18
Spread a thin layer of jam (about 1 teaspoon) on each bottom layer, then top with middle layers.
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19
Spread another layer of jam on each middle layer.
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20
Top with third cupcake layer, pressing gently on top so layers adhere.
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21
Filled cupcakes can be stored up to 3 days at room temperature in airtight containers.
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22
Dust with confectioners sugar just before serving.
