Preheat the oven to 350°F / 180°C and line a muffin tin with cupcake liners.
Mash the bananas up either with a fork or in a stand mixer.If using a mixer, there's no need to clean the bowl before the next step, just put them in a separate bowl and set aside.
Beat the butter together with the white sugar and light brown sugar until fluffy.
Beat in the eggs, one at a time.
Add the mashed bananas and vanilla extract, mix until combined.
In a large bowl, sift together all the dry ingredients and stir together. Then add half of the flour mixture to the cupcake batter and mix on low speed until combined.
Add the oil and milk, then mix slowly until totally incorporated.
Add the remainder of the flour mixture and mix until combined.
Divide the cupcake batter between the cupcake liners, filling them ¾ full.
Bake for 18 - 22 minutes, or until they are slightly springy and a skewer inserted comes out clean.
Remove the cupcakes from the oven and let them sit in the pan for 10 minutes before moving to a wire rack to cool.
The bananas should be very ripe, the browner the better!*For the Frosting:If you are using spreadable cream cheese from a tub, instead of a block of cream cheese, you may need more powdered sugar in order to thicken the frosting enough. Add an extra cup (120g) of powdered sugar. You can also chill the frosting once it has been mixed together in order to make it a little stiffer before decorating your cakes. Get the frosting instructions in my brown butter cream cheese frosting recipe post.