Place butter and coffee beans in a small saucepan on medium-low heat.
Once butter is melted, remove from heat and cover the saucepan to let the beans steep in the butter for 15 minutes.
Use a sieve to remove the coffee beans from the melted butter. Try to get as much butter off the coffee beans as you can. Don't worry if you can't get it all; I had you melt more butter than you need for the biscuits for that very reason.
Chill the coffee butter in the refrigerator.
Once the butter is cold, preheat oven to 400 °F.
Whisk flour, sugar, baking powder, salt, and baking soda in a medium-sized bowl.
With your hands, work 4 1/2 ounces of cold coffee butter cut into small pieces into dry ingredients until the mixture resembles a coarse meal. If for some reason you don't have enough coffee butter, you can add some regular unsalted butter.
Add buttermilk and stir until clumps form.
Knead mixture briefly until it just holds together. The key to flaky biscuits is to not overwork the dough. You want to be able to see chunks of butter in the dough - stop mixing before the butter melts and everything gets smooth.
Transfer dough to floured counter and pat out until 1/2 to 3/4-inch thick.
Use a cookie cutter or rim of a glass to cut out biscuits. A 2" cookie cutter will yield about 9 biscuits.
Place biscuits on a cookie sheet lined with parchment paper or a Silpat.
Bake for 12 minutes or until the tops start to brown.
Spread dark chocolate cinnamon butter on the biscuits while they are still hot!