Set oven to 350°F/180°C/160°C fan, and line an 8-inch (20cm) square dish with parchment paper*.
In a medium bowl, blend the butter and sugar together till fully combined, then beat in the egg, salt and vanilla.
½ cup melted butter, 1 cup brown sugar, 1 large egg, ¼ teaspoon salt, 1 teaspoon vanilla extract
Fold in the flour and chocolate chips and gently mix till the batter is moistened through.
1 cup all-purpose flour, ¾ cup chocolate chips
Pour into the baking pan and bake for 20-25 minutes, till a toothpick inserted into the middle comes out clean. Cool before removing from the pan then slice into rectangles.
*Rub a tiny amount of butter round the interior of the baking dish so that the parchment paper doesn't move around.
Adding extra ingredients - Mix in half a cup of toffee pieces into the batter for extra gooeyness, dried fruit, or chopped toasted nuts for a crunchy texture. If you are adding any of these extra ingredients, gently fold them in when you add the flour.
Adjustments - For sweeter blondies, use 1 cup of dark brown sugar or ½ cup dark and ½ cup light brown sugar for less sweet blondies.
Bake for 20 minutes for gooey centres, or 25 minutes for less gooey.
The blondies will be a light golden colour when done.
Allow the blondies to cool in the pan for several minutes before attempting to remove them.
Double the recipe for twice as many blondies and use a larger dish (13x9 inches/30x20 cm). The blondies will be slightly thicker so they may require a few minutes longer in the oven.
Serve them warm with a scoop of ice cream or at room temperature with a glass of milk for a delicious chocolate snack.
Store in an airtight container and keep in a cool place for up to 3 days, in the fridge for up to 5 days or in the freezer for 3 months.