Preheat oven to 350° F /180°C and place the oven rack in the center of the oven. Line an 8 inch (20 cm) square baking pan with foil or parchment paper and then butter the foil (or spray with a non stick cooking spray).

Place the pecans / walnut / Almonds on a baking sheet and bake for about 8 minutes or until brown and fragrant. Remove from oven, let cool, then chop coarsely.
Meanwhile, in a small saucepan, melt the butter. Remove from heat and let cool to room temperature.
In a bowl, whisk together the flour, baking soda, and salt.

In the bowl of your electric stand mixer, fitted with the paddle attachment (or with a hand mixer), beat the egg, brown sugar, and vanilla extract until light and frothy. Beat in the melted butter. Then, on low speed, beat in the flour mixture until incorporated. Fold in the chopped pecans / walnuts / Almonds and chocolate chips.
Pour the batter into the prepared pan, and smooth the top with an spatula or the back of a spoon.

Bake for about 25 minutes, or until the top is dry, golden brown, and a toothpick inserted into the center comes out with a few moist crumbs. Remove from oven and place on a wire rack. Cool completely before cutting into bars.
Can be covered and stored at room temperature for two to three days, or they can be frozen.