In a medium saucepan set over medium-high heat, melt the butter.

Then stir in the brown sugar and lemon juice. This will look similar to wet sand in the first stages.

Bring mixture to a boil and stir frequently for about 3 minutes, until it becomes smooth.

Slowly add in the heavy cream. It will sputter as you add it. Whisk it to combine. Bring back to a boil and continue cooking and stirring for 4-5 minutes.

Add the vanilla and salt. Stir to combine.

Then pour butterscotch sauce into a glass bowl or jar to cool. *Note that the sauce thickens as it cools. You will use 1/3 Cup of this butterscotch sauce for the brownies. Save the rest for up to 2 weeks in the fridge!

Preheat oven to 350 degrees F. Line an 8 x8 square baking pan with parchment paper, leaving overhang on either side.

In a saucepan set over medium heat, melt the butter.

In a large bowl, whisk together the granulated and dark sugars with the salt.

Then pour over the melted butter and whisk for a minute until smooth.

Add the eggs and vanilla extract and mix vigorously for about two minutes until glossy and smooth.

In a small bowl, mix together the flour and cocoa to remove any lumps. Then add this to the egg mixture. Whisk well to combine.

Use a spatula to fold in the chocolate chips and optional nuts. Then pour into prepared pan. Bake for 26-30 minutes. Brownies should be just set and no longer wobbly. *PLEASE DO NOT OVERBAKE!!!

Allow the brownies to cool for at least an hour. *I know, I know. But they need to be set before you douse them in sauce!

Then take about 1/3 cup of the butterscotch sauce and pour in the center of the brownies. Use a knife to gently spread around. Then sprinkle on flaky sea salt.

*The butterscotch will get thicker and set as it cools. If you made it in advance then microwave it for about 15 seconds to loosen before pouring on brownies.

Feel free to let the butterscotch set for about 30 minutes before cutting into these. Or if you cannot wait one more minute, then dig in and have napkins handy!