Combine strawberries, rhubarb, 4 tablespoons of sugar, water, and Rodelle Almond extract in a medium heavy saucepan.
Bring to a boil, reduce heat and simmer for 15 minutes. Remove from heat and cool.
Preheat oven to 350°. Grease muffin tin cups with vegetable spray or butter.
In a food processor, mix almond flour, powdered sugar, and salt until combined, about 30 seconds.
Add eggs and almond extract and process until smooth, about 30 seconds.
Pulse in the melted butter, cornstarch, and baking powder. Scrape mixture into a large bowl.
Using an electric beater, whip egg whites until very foamy. Gradually add 2 tablespoons granulated sugar while beating egg whites until stiff peaks form.
Using a rubber spatula, gently fold one third of the egg whites into the almond mixture to lighten it.
Fold in the rest of the egg whites just until no streaks remain.
Spoon batter into prepared muffin cups, and bake for 10 minutes.
Remove from oven. Spoon 1 teaspoon rhubarb mixture on top of each cake. Return to oven, and bake until golden brown and until a toothpick inserted in cake (not the jam) comes out clean, about 8 to 10 minutes.
Serve warm or at room temperature, preferably within 8 hours of baking.
