In a mixing bowl, whisk together the flour, baking powder and salt. Stir in the cinnamon and set aside.
Using a stand mixer fitted with the flat beater (or paddle) attachment, cream together the butter and sugar until well combined. Add in the vanilla and the egg and mix together until combined. With the mixer on low, slowly add in the dry ingredients and mix until the dough comes together. Remove the cookie dough from the mixer.
On a clean, flat surface, divide the dough in half and shape into logs. Wrap with plastic wrap and refrigerate for at least 2 hours, or overnight.
When ready to bake, preheat your oven to 350° F. Unwrap the cookie dough and slice. Place the cookie dough slices on a parchment paper-lined baking sheet and lightly brush the cookies with almond milk and bake for about 12 to 15 minutes, or just until the edges turn golden brown.