Sieve the maida and baking powder in a bowl and keep aside.
In another bowl, whisk the soft butter and powdered sugar.
Pour in the condensed milk and mix.
Pour in about 2 tablespoons of milk and mix again.
When the batter is is smooth and airy, add in the maida in small portions at a time and keep folding it in the butter batter.
Keep adding milk accordingly to mix the flour in the batter.
Now add the blueberries, choco chips and walnuts and mix them in lightly.
Pour in the vanilla essence, mix once again.
With the help of a spatula put them in colourful silicone muffin moulds.
Place them on microwave low rack, maintain a distance between the cups as they rise.
Set the temp to 180* on microwave convection mode and bake for 20 minutes.