Preheat the oven to 160C (fan) and line up 24 x 20 cm rectangular baking tin with baking parchment. Set aside.
In a bowl of a freestanding mixer fitted with a paddle attachment or handheld electric mixer, beat together the butter and both sugars until pale and fluffy, about 3 minutes. Add vanilla and eggs, one at a time, scraping the bowl well after each addition. Mix well until combined.
In a separate bowl mix together the flour, baking soda and salt. Slowly add the flour mixture to the butter mixture and using spatula or a wooden spoon, mix until just combined. Fold in the chopped walnuts and chocolate chips/ chunks and transfer the batter into baking tin. Smooth the top with back of the spoon or spatula and bake for 20 minutes or until golden brown on top but the middle has still a bit of a wobble to it. Toothpick inserted into the middle may not come out clean and should have few crumbs attached to it. Do not over-bake!
Allow the blondies to cool in the tin for about 5 minutes, then transfer to a cooling rack to cool completely. Slice into squares and enjoy!