Place first 3 ingredients in a food processor, and process until well blended. Add butter, and pulse 4 to 5 times or just until combined.
Add the eggs, 1 at a time, pulsing 1 or 2 times after each addition. Add buttermilk, vanilla, and lemon juice; pulse until blended.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, baking soda, and salt in a large bowl, stirring with a whisk.
Make a well in center of mixture. Add buttermilk mixture; stir just until moist.
Gently fold in raspberries. Let batter stand 5 minutes. Spoon batter into 12 muffin cups coated with cooking spray. Sprinkle with turbinado sugar. Bake at 375° for 22 minutes or until muffins spring back when touched lightly in center.
Remove muffins from pans immediately; place on a wire rack.