Recipe courtesy of Judy's Kitchen ( 
Adapted from Kikkoman Crunchy Topping Coffee Cake
Rating:  9 out of 10
2/3 cup brown sugar
1 Tbsp. cinnamon
6 Tbsp. butter, melted and slightly cooled
2/3 cup Kikkoman Panko Breadcrumbs
2/3 cup toasted chopped pecans

Heat oven to 400F (375F for dark or coated pans.)  Adjust oven rack to upper middle position.  Spray 2 (12-cup) standard-size muffin tins with nonstick cooking spray.  In medium bowl, combine ingredients with fork.  Set aside. 

3 cups unbleached all-purpose flour
2/3 cup sugar
1 Tbsp. baking powder
1 tsp. kosher salt or fine sea salt
1 tsp. baking soda
3/4 cup semi-sweet chocolate chips
2/3 cup vegetable or canola oil
2 large eggs
1 cup nonfat Greek yogurt, plain or vanilla flavored
1 tsp. pure vanilla extract (I used my homemade vanilla.)

In large bowl, sift together flour, sugar, baking powder, salt and baking soda.  Stir in chocolate chips.
In medium bowl, whisk together oil, eggs, yogurt and vanilla.  Pour over dry ingredients and lightly stir with spatula or spoon till just barely combined.  Some lumps are okay.  Do not over mix.  Divide  the thick batter evenly into muffin wells, using about 2-3 Tbsp. per muffin.  Spoon about 1-1/2 tsp. topping over each.  Bake 13-16 minutes (mine took 15 minutes).  Cool in pan 3-4 minutes, then transfer to wire rack to finish cooling.    Yield:  24 standard-size muffins