Use an electric hand mixer to beat the cream cheese until smooth.
Gradually add the butter 2 Tablespoons at a time, and continue beating until smooth and well blended.
Add the lemon zest, extract, juice, and powdered sugar all at once. Blend until combined and smooth. Spread or pipe over cakes/cupcakes.
Notes
YIELD: 1 1/2 cups frosting, which will frost about 12-15 cupcakes.
CREAM CHEESE: I prefer full-fat Great Value cream cheese for this frosting, but (Great Value) 1/3 less fat Neufchatel cheese will still work. Philadelphia cream cheese is much lighter, softer, and doesn't work as well for some reason. So save some money and use the store brand.
BUTTER: You may use salted or unsalted butter, depending on your preference.