Banana Streusel Muffins

I pulled this out of Better Homes and Gardens a few months ago. The original recipe is for a loaf, but this morning I made them into muffins.

Muffin Batter
2 cups flour (I used a fine ground whole wheat flour)
1 1/2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. cinnamon
1/4 tsp. salt
1/4 tsp. ground nutmeg
1/8 tsp. ground ginger
2 eggs, lightly beaten
1 1/2 cups mashed banana (4-5 medium, I used 3 large)
1 cup sugar
1/2 cup oil
1/4 chopped walnuts, optional


Streusel Topping
1/4 cup packed brown sugar
3 Tbsp. all-purpose flour
2 Tbsp. butter
1/3 cup chopped walnuts, optional

Preheat oven to 350 degrees.
In large bowl, combine dry ingredients; set aside.
In mixing bowl, combine eggs, mashed banana, sugar, and oil. Add egg mixture all at once to flour mixture. Stir just until moistened (batter should be lumpy). Fold in walnuts.
To make streusel: combine brown sugar and flour, cut in butter until mixture resembles coarse crumbs, sprinkle over batter.
Spray muffin tins with cooking spray.
Scoop batter into pans two-thirds full.
For mini size muffins, bake about 13-15 minutes. For regular size muffins, around 18-20 minutes.
Remove from oven, let sit in pans for a couple minutes, then remove to wire racks to cool.

Some Hints:
* I keep a bag of frozen bananas in my freezer, they thaw well, and I've read they add more flavor.
* Use a cookie scoop to fill tins two-thirds full, for my scoop that's 1 scoop for mini size, 2 1/2 for regular size. This makes for even cooking and is so much easier than trying to pour it in.
* If you want the streusel to have more crunch, try adding streusel five or so minutes into baking while batter is still thin, if you wait too long, it will just fall off.
* I always err on the side of underdone, rather than overdone, muffins will continue to cook out of the oven, but I must admit, I've had my fair share of sunken muffins.
* Remember to remove muffins from their tins after a few minutes, they can get overcooked sitting in hot pans.
* Use light colored pans. Dark, non-stick pans will yield dark pastries. I read this a long time ago and as weird as it sounds, it is true.
* Whatever is not eaten immediately, should be put in the freezer the same day. Baked goods thaw really well,  in fact, I think it seals in the moisture, I don't have the science to back it up, just something I've noticed.
* If you want to make this into bread, increase cooking time to 55-60 minutes, may need to cover with foil the last 15 minutes to prevent overbrowning.