Coffee Banana Muffins

My sister, Sarah, just sent this which usesd leftover coffee and banana to make incredible coffee banana walnut muffins:

1 pkg Krusteaz Crumb Cake Mix
1 egg
2/3 c strong!!! Coffee
1 over ripe banana
Butter softened
Walnuts (optional)

Mix first three ingredients until lumpy and moistened. Add soft banana with fork and mash into lumpy batter.

Line muffin tin with paper cups. Spoon 1/3 batter into cup, top with some cinnamon topping (from box mix). Add pinch-1/8 t soft butter, chopped walnuts, layer with more batter, top with cinnamon topping and walnuts to fill cup.

Bake 350 for 23 minutes.