Place butter in a 2-qt. microwave-safe bowl. Heat, uncovered, at 50% power for 20-30 seconds or until softened. Add brown sugar; stir until creamy. Add flour, oats, vanilla, salt and baking soda; mix well. Pat half of the mixture into a greased 8-in. square microwave-safe dish. Microwave, uncovered, at 70% power for 3-1/2 to 4-1/2 minutes or until mixture sets, rotating a half turn after 3 minutes. (Crust will be uneven.) Spread with jam. Sprinkle with remaining dough; press down lightly. Cook, uncovered, at 70% power for 3-4 minutes or until set, rotating a half turn after each minute. Serve warm.