Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius) and line a 12-cup muffin pan with cupcake liners.

Combine sugars, baking powder, cinnamon, and salt. Whisk in the melted margarine. Add the flour, mixing well with a fork, until crumbs form.

Spread out on a piece of Gefen Parchment Paper until ready to use.

In a large mixing bowl, combine the first six ingredients.

Add eggs and stir gently. Add melted margarine and whisk very well until a thick batter forms.

In a separate bowl, combine plums with raspberry jam until well-coated.

Place two heaping tablespoons of batter into each muffin cup. Add a large spoonful of diced plums into the center of each muffin and top generously with crumbs. (You may have some extra crumbs and/or plum mixture.)

Bake for about 30 minutes or until lightly golden.

Cool in the pan for 20 minutes and then transfer muffins to a wire rack to finish cooling.