Preheat oven to 350F and line a 9x13” baking pan with parchment paper.
In a large bowl, combine the butter and sugars and whisk until incorporated.
Add in the eggs, egg yolk, molasses, and vanilla and whisk for another 2-3 minutes.
Add in the flour, spices, salt, and baking soda. Stir until just combined.
Fold in the toffee and dark chocolate chips.
Spread batter evenly in the baking pan.
Bake for 28-30 minutes.
Sprinkle with flaky sea salt and allow to cool fully before cutting.