These easy Plum Bars are fruity dessert squares made with a buttery oat crumble base, a sweet-tart fresh plum filling, tender crumb topping and baked until golden.
Pre-heat oven to 350°F/180°C. Line a 9×9-inch (23cm) pan with parchment paper.
In a large mixing bowl, whisk together the flour, oats, both sugars, ginger, baking powder, and salt together well. Using a pastry blender or your fingertips, cut or rub in the butter until large crumbs form. Set aside 1 cup of the crumb mixture (to use as the topping).
Press the remaining crumb mixture firmly and evenly into the bottom of the baking pan and set aside.
Add the plums, sugar, and ¼ cup of water to a pot and simmer for 10 minutes until the plums break down. Mix the cornstarch into 1 tablespoon of water and mix it into the plums and cook for a further minute. Stir in the lemon juice. You can mash or blend the plums to a puree, or leave some chunks for texture. Set it aside to cool slightly.
Spread the plum mixture evenly over the crust in the baking tray, then sprinkle the remaining crumb mixture loosely over the top.
Bake for 45 minutes or until the crumb topping is golden and the plum filling is bubbling.
Allow the oatmeal plum bars to cool in the pan, then remove from the pan and cut into bars.