I apologize in advance for all the diets I am about to destroy with this recipe. These squares are pure, unadulterated evil in cookie form - you will have to hide them from yourself if you want to have any left to serve your guests.
1 cup butter
1 cup light brown sugar
1 egg yolk
1 1/2 cups all-purpose flour
1/4 tsp salt
1/2 cup light corn syrup
1/4 cup 35% cream
1 tsp vanilla
1 1/4 cups semi-sweet chocolate chips
1 cup pecans, lightly toasted and chopped
Preheat the oven to 350°F (180°C). Line a 9 x 13 in. (23 x 33 cm) rectangular baking pan with foil - bring the foil up to cover the sides of pan. Grease the foil.
From the total amount, remove ¼ cup (50 mL) of the butter and¼ cup (50 mL) of the brown sugar to a 4 cup (1 L) microwave-safe bowl or measuring cup. Set aside.
Place the remaining butter and brown sugar in a mixing bowl and beat with electric mixer until smooth. Add egg yolk and continue beating until well combined. Add the flour and salt, and mix until completely incorporated. Press the dough evenly into the bottom of the prepared pan. Place in the preheated oven and bake for 18 to 20 minutes or until the dough is slightly puffed in the centre and beginning to brown. Remove from oven and let cool while you prepare the topping.
To the measuring cup with the reserved butter and brown sugar, add the corn syrup, whipping cream and vanilla. Place in the microwave and heat on high power for 4 minutes - stirring the mixture after each minute. It will foam up quite dramatically - very exciting to watch! Remove from the microwave and pour over the pre-baked crust in the pan. Return the pan to the oven and continue baking for an additional 18 to 20 minutes, or until the topping is bubbly.
Remove from the oven and sprinkle the chocolate chips over the surface. Let sit for about 5 minutes to allow the chocolate to melt, then spread evenly over the top with the back of a spoon. Sprinkle the chopped pecans over the melted chocolate and let cool completely before cutting into squares and removing from the pan. (I like to cut them into 8 strips along the long side and 6 strips along the short side to make quite small squares.)