Jennifer's Amazing Muffins with Streusel

My friend Jennifer made the most AMAZING muffins! They were so delicious- I had way more then my fair share (but I don't regret that one bit!) Anyway- I begged her for the recipe (I even took a picture- they were that good!), and she posted it on her blog, so I thought I would pass it along to all of you since it was so good. Mostly I was amazed with her streusel- it was perfect! I think she added mashed banana to the ones that I had.

"I just LOVE muffins! So I thought I would share the best muffin recipe. It is the best because you can use whatever schtuff you have on had that needs to be used up. I've tried brown bananas, smashed sweet potato, chopped up apples with applesauce, grated carrots, overripe peaches...I've even tossed in some leftover oatmeal...and every single time I get a yummy moist muffin!
So go dig around in your fridge. Find something mushy. Make muffins!"

MUFFIN:
about 2 cups schtuff (see list above)
3/4 cup sugar
1 egg
1/3 cup butter
1 1/2 cups flour
1 tsp. baking soda
1 tsp. baking powder
1/2 tsp. salt
1/2 tsp. cinnamon (optional)

STREUSEL: (optional, but really, really good)
1/4 cup sugar
3 TBSP flour
1/4 tsp. cinnamon
2 TBSP cold butter

Preheat oven to 375 degrees. Mash your schtuff. Add wet ingredients and blend. Gently add dry and mix until just moistened. (Overmixing will make rubbery muffins). Scoop into a greased 12 hole muffin pan.
To make the streusel, measure the sugar, flour and cinnamon into a small bowl. Cut the butter in with a fork until incorporated and crumbly. Sprinkle evenly atop muffin batter.
Bake at 375 degrees for 19 minutes or until a toothpick inserted comes out clean.