For the cake, grease and flour two 8 1/2 inch round cake pans. Line the bottom with parchment paper. Set aside.
For the streusel, combine flour, sugars, cinnamon and butter in small bowl. Mix with hands until crumbly. Set aside.
In a large mixing bowl, beat flour, sugar, baking powder, baking soda and salt on low until combined. Beat in softened butter until mixture is crumbly. Add in eggs, vanilla and buttermilk and beat until fully combined and fluffy. Pour half of mixture in bottom of cake pans, dividing evenly. Spread using the back of a spoon or a small offset spatula (yes it will be very thin, it's okay!) Top with half of the streusel, sprinkling it over both cakes. Add half of the chocolate chips, about 1 cup, dividing evenly between both cakes.
Pour the remainder of the batter over the cakes, dividing evenly. Use your spatula or spoon to spread it out one more time. Top with the remaining streusel and chocolate chips.
Bake cakes in a 325 degree F oven for 30-35 minutes. Remove and cool 15 minutes, then remove cake from pan onto a wire rack. Cool completely.
Serve into slices or freeze in an airtight container for later use. ENJOY. Best used within 3 days of baking (if not freezing).
Notes
Be sure to let the butter soften at room temperature before you make this recipe.
Use an offset spatula to smooth the first layer of cake batter into the bottom of the pan in an even layer. After adding the streusel and chocolate chips and the rest of the batter, smooth that layer too.
Use red and green chocolate chips or holiday sprinkles (M&M's) for a festive holiday version of this cake or go with regular for a year-round coffee cake. You can also try this recipe with half regular chocolate chips and half white chocolate chips. Or try dark chocolate chips.
Cool the cake completely before you slice it. It’s hard to wait to dig in, but this allows it to set up properly.
Serve coffee cake for breakfast, brunch, dessert or an afternoon treat. Don't forget the coffee!
Store the second coffee cake in the freezer for another time or gift it to a friend, neighbor or family member. It also makes a great hostess gift at the holidays!