Heat oven to 350°F. Line 12 medium muffin cups with paper baking cups or spray bottoms only with no-stick cooking spray. In mixer bowl, beat together sugar, peanut butter and oil until creamy. Add bananas, egg and lemon juice; beat until blended. Combine flour, baking powder and salt; add to banana mixture, stirring until just moistened. (Do not overmix.) Gently stir in Prunes; fill muffin cups three-fourths full. Sprinkle tops with peanuts; bake 18 to 22 minutes or until wooden pick inserted in center comes out clean. Cool in pan 5 minutes; remove from pan. Serve warm or cool completely on wire rack.
Tip: To make mini-muffins, line 36 small (1 3/4-inch) muffin cups with paper baking cups or spray bottoms with no-stick cooking spray. Bake 12 to 14 minutes or until wooden pick inserted in center comes out clean. (Makes 3 dozen mini-muffins)