Preheat the oven to 375℉. Line two muffin pans with 15 liners.
PREPARE THE CUPCAKES:
In a medium bowl, sift the flour, baking powder and salt together.
In a separate, larger bowl, use an electric mixer to combine the butter and sugar until light and fluffy. Add in eggs, one at a time, beating after each addition to incorporate. Mix in the lemon zest, lemon extract and vanilla extract.
Gradually add the dry ingredients to the butter mixture, ⅓ at a time, alternating with ½ of the milk after each of the first two additions of flour. Beat in the lemon juice, just until combined.
Fill the prepared cupcakes liners with the batter (¾ full); bake 15 to 17 minutes, until a toothpick inserted into the center comes out clean. Let the cupcakes cool before adding frosting.
MAKE THE FROSTING:
In a large bowl, with a hand or stand mixture, cream together the sugar and butter on low speed. Mix until well-blended. Increase the speed to medium and beat for another 3 minutes. Add the lemon extract and 2 tablespoons of the cream and continue to beat on medium-speed for 1 minute more, adding a little more cream if needed for desired spreading/piping consistency.
FROST THE CUPCAKES:
Frost cupcakes using a piping bag, if desired. Or simply spread the frosting on top.