Heat oven to 180 degrees C/320 degrees F
In a food processor, blitz the butter and stevia until they come together.
Next, add the plain flour, almond meal, cream of tartar, bicarb, eggs, and vanilla bean paste. Blitz again in the food processor until combined.
Peel the bananas and break into pieces, adding to the food processor. Blitz again until the banana is all mixed in.
Remove the blade from the food processor and gently stir in the blueberries and chocolate chips with a spoon.
Lightly spray two, six hole silicone muffin trays with canola spray.
Using a dessert spoon, spoon the batter evenly into all 12 muffin holes, smoothing the tops as you go.
Bake in oven at 180 degrees C/320 degrees F for 20 minutes or until golden brown.
Cool on a wire rack before taking out of the muffin cases.
Store muffins in an air tight container at room temperature for 3 to 4 days. Otherwise freeze in ziplock bags for upto 6 weeks. Pop in the microwave for 30 seconds before eating.