Beat softened butter and sugar for 5–6 minutes until pale and fluffy.
Add room-temperature eggs one at a time, mixing well between each.
Mix in lemon extract, vanilla extract, and optional fresh lemon zest.
Add flour in portions, alternating with the 7Up, mixing just until combined.
Grease and flour a bundt or angel food cake pan generously.
Bake at 325°F for about 1 hour and 10 minutes or until a toothpick comes out clean.
Let rest in the pan briefly before releasing onto a cooling rack.
Whisk powdered sugar, milk, and lemon flavor until smooth.
Drizzle the glaze over the cooled cake.
