Preheat oven to 350°. Line 2 (12-cup) standard muffin pans with 15 baking cups; spray with cooking spray.
In large bowl, with mixer on medium-high speed, beat cream cheese and 1/4 cup sugar 2 minutes or until light and fluffy. Add 1 egg and 1 teaspoon vanilla extract; beat on high 1 minute or until smooth. Transfer to small zip-top plastic bag. Makes about 1 1/2 cups cream cheese mixture.
In medium bowl, whisk flour, baking powder, baking soda and salt. In separate large bowl, mash bananas; whisk in oil, and remaining 1/2 cup sugar, 1 egg and 1 teaspoon vanilla extract. Add flour mixture to banana mixture; stir until just combined and fold in walnuts. Makes about 4 cups batter.
Divide batter into prepared cups; snip bottom corner of plastic bag with kitchen scissors and squeeze heaping 1 tablespoon cream cheese mixture into center of batter in each cup. Bake muffins 20 minutes or until golden brown and toothpick inserted in center of muffins comes out clean; cool 15 minutes in pan. Makes 15 muffins.
