Preheat the oven to 176 degrees celsius.
Line 1-2 large baking sheets and keep aside.
Take a large bowl and whisk the butter with the help of a hand mixer until it is soft and creamy.
Slowly add in the sugar and beat continuously.
Next, break the egg and add it in along with the vanilla extract. Blend all this well with the hand mixer.
Take a separate bowl and sieve in the all purpose flour, baking powder, cocoa powder and salt in it and keep aside.
With the help of a spoon, mix in 1/3rd of the flour mixture into the butter mixture bowl. Blend both these mixtures well.
Continue this process of adding 1/3rd flour mixture and blending until it is completely over.
Finally add in the walnuts and chocolate chips into this finely blended mixture.
Carefully place tablespoonfuls of cookie dough on the baking sheets placing them about 1 inch apart. Press the cookie dough down softly towards the baking sheet.
Bake for 8 -10 minutes till the sides are lightly coloured.
Once cooked, remove and let them cool on the baking sheets.
Serve warm with milk.