Combine wet cake ingredients and mix well. Add dry ingredients and mix thoroughly. Spread in an 8 x 8 glass baking dish lined with parchment paper and sprayed with cooking spray.
Microwave for 4 minutes or until the entire top is dry to the touch. Cool completely. Gently lift the parchment paper to remove the cake from the baking dish.
Meanwhile, use an electric mixer or whisk to combine the filling ingredients. Mix until smooth.
Spread the filling on the cooled cake. Gently roll up. Refrigerate for at least 3-4 hours before serving.
Notes
I'm sure you can bake this if you prefer not to use a microwave. I would bake it for 12-15 minutes at 350 or until the top is dry to the touch and the cake springs up when lightly pressed.