Preheat oven to 350 degrees. Prepare cupcake/muffin pan with paper muffin liners.
With electric mixer on high speed, whip egg whites with salt and cream of tartar until soft peaks appear. With mixer running, add sugar, 1 tablespoon at a time, until stiff peaks form.
In a clean bowl beat the egg yolks with the peanut butter, vegetable oil and vanilla extract with the mixer until very smooth. Add the ground almonds and baking soda. Mix well. Add the beaten egg whites and mix with a spatula or spoon until batter is no longer streaky.
Put about 2 scant tablespoons of batter in the bottom of each prepared muffin cup. Add 1 teaspoon of jam to each cupcake and top with remaining batter.
Bake for 20 – 25 minutes until the cupcakes have risen, are golden brown and springy to the touch.
Cool on a rack until completely cooled before frosting.
In the bowl of an electric mixer blend together the cream cheese, butter and vanilla extract. Turn mixer off and add powdered sugar. Start mixer again on low speed and blend in the sugar increasing the speed until the mixture is very smooth. Add the jam and mix until just mixed in.