Preheat oven to 375 degrees F.
Line a small oven safe vessel (or ramekin depending on how many portions you are making) with parchment paper. Grease the sides and bottom of lined pan with nonstick spray. Set aside.
In a mixing bowl, stir together cherries, cornstarch and lemon juice.
In a large mixing bowl, stir together melted butter and brown sugar. Add flour, oatmeal, baking powder and salt and stir with a fork until the mixture resembles crumbs.
Press half of the crumb mixture into the bottom of prepared pan.
Spread cherry filling over the crust.
Sprinkle remaining crumb mixture over cherries.
Bake bars for about 20 minutes OR until the top is golden.
Let cool for 10 to 15 minutes before potioning.