Preheat the oven
to 350°F/180°C/gas 4. Arrange 20-24 foil baking
cups on baking sheets.
Sift the flour, baking
powder, and salt into a medium bowl. Beat the
butter, sugar, and vanilla in a large bowl with an
electric mixer at medium speed until creamy.
Add
the eggs, one at a time, until just blended after
each addition. With mixer at low speed, gradually
beat in the dry ingredients, alternating with the
milk and lemon juice.
Spoon the batter into the
baking cups, filling them half full. Bake for
10-15 minutes, or until golden brown. Cool the
cakes on racks.
With mixer at high speed, beat the
cream in a medium bowl until stiff. Cut a small
circle about 1/2-inch (1-cm) deep from the top of
each cake.
Fill with 1/2 teaspoon of jam and 1
teaspoon of whipped cream. Cut the tops in half and
arrange like butterfly wings.