Dough: Cream together softened butter and granulated sugar in a large bowl using an electric hand mixer or stand mixer until light and fluffy. This should take about 1 minute. Beat in the baking powder, baking soda, salt, vanilla extract and nondairy milk until ingredients are evenly distributed. Beat in the flour until just combined. Do not over-mix.
Bake: Press the dough evenly into the bottom of the prepared baking pan. Mix together the granulated sugar and ground cinnamon in a small bowl. Sprinkle the mixture evenly over the top of the dough. Place pan on center rack of preheated oven and bake for 30 minutes.