Maple Pecan Sweet Potato Muffins

What a great way to use my abundance of CSA sweet potatoes! I was totally thrown though by the inclusion of imitation maple extract in this otherwise lovely recipe. Needless to say, I didn't use any and instead upped the amount of maple syrup. I also subbed buttermilk for the sour cream. The muffins here have a lovely texture and a great flavor, seriously enhanced by the Maple Pecan Streusel. And the addition of freshly grated lemon rind is brilliant. Yield was 10 Texas-Sized muffins.