Combine blackberries, maple syrup, corn starch, and 1/4 cup water in a medium saucepan. Bring to a low boil, mashing berries to break them down. Reduce heat to medium-low; cook until thickened, about 5 minutes. Remove from heat, and let cool slightly.
Preheat oven to 350°F. Coat an 11- x 7-inch baking dish with parchment paper; lightly grease with cooking spray. Combine oats, flour, coconut sugar, and salt in a medium bowl. Stir in butter, oil, and vanilla; mix with your hands until texture resembles coarse sand. Reserve 2/3 cup oat mixture.
Spread remaining oat mixture in an even layer in prepared baking dish. Use your hands or the bottom of a measuring cup to firmly press down. Spread blackberry mixture evenly overtop, and sprinkle remaining oat mixture over berries. Bake until lightly browned, about 35 minutes.
Cool completely on a wire rack. Slice into 12 squares. Top each square with a dollop of So Delicious Coconutmilk Yogurt Alternative, if desired. Store in an airtight container up to 4 days.