Preheat oven to 375 degrees F. Lightly coat a 2-quart baking dish with nonstick cooking spray. Toss pear slices with 1 tablespoon flour and arrange in the bottom of the prepared dish. Top pears with half of the grapefruit slices and sprinkle with half of the chia seeds. Repeat with remaining grapefruit and chia seeds. In a medium bowl combine the brown sugar, oats, 1/4 cup flour, flaxseed meal, and pumpkin seeds. Cut in butter until mixture starts to cling together. Sprinkle fruit mixture with oat mixture.
Bake for 30 minutes or until fruit mixture is bubbly and top is brown. Serve with whipped cream or yogurt, if desired.