Preheat oven to 350°. Grease and flour a 10-inch bundt cake pan.
Whisk together the flour, baking soda, baking powder, cinnamon, and sea salt. Set aside.
With an electric mixer, cream the butter. Add the brown sugar and granulated sugar ¼ cup at a time and mix into the butter until light and fluffy. Scraping the sides of the bowl as needed to mix all the sugar in.
Add the vanilla and then the eggs one at a time, scraping the sides of the bowl after each egg.
Mix the coffee and oat milk together in a cup.
Add the flour and coffee mixture to the mixture at the lowest/stir setting. Mix a little at a time alternating between the coffee mixture and flour until it is all incorporated in the mixing bowl.
Pour the batter into the bundt cake pan. Bake about 45 minutes or until a toothpick inserted in the middle comes out clean.
Cool the cake for 10 minutes. Then invert it onto a cooling rack lined with parchment paper. Cool completely.