Preheat oven to 375º.
To prepare filling, combine the first 6 ingredients, tossing well. Spoon mixture into an 8-inch square baking dish coated with cooking spray.
To prepare topping, place oats in a food processor, and pulse until coarsely ground. Add lavender buds, and pulse 8 times or until combined. Place oat mixture in a large bowl. Lightly spoon flour into dry measuring cups; level with a knife. Add flour, 1/2 cup sugar, and salt to oat mixture; stir to combine. Cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Add 3 tablespoons honey to oat mixture; stir just until moistened. Sprinkle topping over filling. Bake at 375º for 30 minutes or until golden and bubbly.