Preheat the oven to 350°F. Spray an 8x8-inch baking pan with cooking spray or line with parchment paper

In a small saucepan on medium heat, brown the butter. Stir constantly to ensure no brown bits at the bottom burn. The butter should smell nutty, no longer foamy, and be light brown. As soon as it reaches this stage, scrape it into a bowl (this can happen fast!). Allow it to cool for 10 minutes

Add brown sugar, 1 large egg, and vanilla extract (and almond if using) into the browned butter. Whisk the ingredients together until smooth

After it is smooth, add in the flour and salt. Fold in the chocolate chips and toffee bits (you can reserve some for the top to ensure chocolate pokes out of each bar). Pour the batter into the prepared pan

Bake for ~25 minutes until the edges just start to pull away. The center will no longer be jiggly but it will still be soft (we cook them just under 25 minutes see note above)

Cool and cut into squares