Bittersweet Mocha Coffee Cake, Gluten-Free

From Art of Gluten-Free Baking:

Note: This recipe uses my gluten-free flower mix:
Jeanne's Gluten-Free All-Purpose Flour Mix (mix together and store in fridge):
1 1/4 C. brown rice flour
1 1/4 C. white rice flour
1 C. tapioca flour
1 C. sweet rice flour (also known as Mochiko)
2 scant tsp. xanthan gum

Special equipment needed:
-A stand mixer is helpful, but a hand mixer will do
-bundt pan

1 C (2 sticks) unsalted butter, softened
1 C sugar
4 large eggs, room temp
1 TBL vanilla extract
2 C Jeanne's Gluten-Free All-Purpose Flour Mix
1/3 C unsweetened cocoa powder
1/2 tsp salt
2 tsp baking powder
3/4 C strong brewed coffee (I actually use decaf instant coffee 'cause it's easy)
1/4 C milk
1 C semisweet chocolate chips
-butter and tapioca flour for pan

-Preheat the oven to 350 degrees
-butter and flour a bundt pan
-make your coffee. Measure out 3/4 C and put in small bowl. Add milk. Set aside
-in large bowl, beat butter until fluffy. Add sugar and beat several minutes more
-add vanilla extract, beat in
-add eggs, one at a time, beating until smooth
-add dry ingredients and coffee mixture to butter mixture, alternating the addition of each, beginning and ending with dry ingredients
-fold in chocolate chips
-transfer batter to prepared pan. Thump the pan on the kitchen counter to get rid of any large air bubbles.

-Bake for about 50-55 mins, or until tester comes out clean

-Cool on rack for 10 minutes, then carefully invert onto cooling rack