Preheat the oven to 350°F. Grease a 9-inch cake pan with butter or cooking spray.
In a mixing bowl, cream together the butter and sugar with an electric mixer until light and fluffy.
Add the eggs, one at a time, beating well after each addition.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the flour mixture to the butter mixture, alternating with the milk, until the batter is smooth.
Stir in the vanilla extract.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake for 45-50 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Allow the cake to cool in the pan for 10 minutes, then remove it from the pan and transfer it to a wire rack.
To make the glaze, whisk together the powdered sugar, milk, and lemon extract until smooth.
Drizzle the glaze over the top of the cake, allowing it to drip down the sides.
Let the glaze set for 10-15 minutes before serving.