Preheat oven to 350 degrees F (175 degrees C). Line a 12-cup muffin tin with paper liners.
Whisk together gluten-free flour blend, sugar, cocoa powder baking soda, baking powder, and salt in a large bowl.
Mash banana in a bowl. Add cooled coffee, oil, almond milk, apple cider vinegar, and vanilla extract. Whisk until combined. Pour into flour mixture. Stir slowly until just combined; batter will be thick and gummy.
Ladle batter into the lined muffin tin, filling cups 2/3 full.
Bake in the preheated oven until a toothpick inserted in the center comes out clean, 18 to 20 minutes.
