1. Preheat oven to 350º.
2. Coat an 8-inch baking pan with cooking spray. Set aside.
3. Combine flour and next 5 ingredients (through salt) in a large bowl, stirring with a whisk.
4. Beat together sugar, yogurt, oil, and egg in a large bowl. Stir in the carrot and pineapple. Mix with dry ingredients. Fold in pecans.
5. Spoon batter into pan. Bake 25 minutes, or until a toothpick inserted in the center comes out clean. Cool.
6. Beat cream cheese in a medium bowl. Add lemon juice. Beat in powdered sugar. Spread frosting over cake. Cut into 12 squares.