I ran out of vanilla extract and only had semisweet chocolate chips so ended up making some changes to the original recipe. It came out OK. I would use a higher quality chocolate next time, with a little less sugar, some vanilla extract and maybe skip the cinnamon. The top came out like a brownie and the inside like a chocolate cake. Here's what I did...
1 1/6 c semisweet chocolate morsels
1/2 c oil
1/2 c yogurt
scant 1 cup sugar
3 large eggs, room temp
1 t almond extract
1.5 c flour
1.5 t baking powder
1/2 t salt
2 heaping teaspoons cocoa powder
Several hefty dashes of cinnamon
Set 12 muffin liners in tray. Preheat oven to 180C.
In a large bowl, combine flour, powder, salt, cocoa, and cinnamon. Make a well in center.
In a medium bowl, combine 1/4 c oil with yogurt, sugar, eggs, and extract.
Melt chocolate and 1/4 c oil in pan over very low heat, stirring constantly.
Add yogurt mixture to dry ingredients and stir slightly (need not be fully incorporated).
Add melted chocolate mixture to the batter and stir.