Prepare a 9"x13" baking pan with baking spray, and preheat your oven to 350 degrees Fahrenheit.
In the bowl of a stand mixer, beat the butter and sugar on medium speed until light and fluffy, about a minute. Add the eggs one at a time, then the vanilla
With the mixer running, add the flour, salt, and baking powder in increments.
Once combined, evenly spread the batter into the prepared pan. Bake at 350 degrees Fahrenheit for about 27 minutes, or until a toothpick inserted in the middle comes out clean.
Combine the 3 milks and coffee in a small bowl or pitcher. Whisk until very well combined.
Once the cake is cooled, poke holes evenly all over it (I used a meat thermometer to poke holes, but you can use a baking dowel or fork prongs). Evenly pour the milk mixture over it, in increments, until it has all been absorbed by the cake. Let the cake sit in the refrigerator for 2 hours to overnight, so the milk has time to absorb.
In the bowl of a stand mixer with the whisk attachment, whisk the heavy cream on medium high speed until soft peaks begin to form. Add the sugar and vanilla and continue whipping until stiffer peaks form, or it reaches your desired consistency. Spread evenly over the top of the cake, then sprinkle with a bit of cinnamon. Serve cold.