Lightly butter a 9x13 or larger baking dish
Heat the butter in a medium saucepan over medium-high heat. When it starts to brown and smell nutty, remove it from the heat and stir in the chocolate and cocoa. Let slightly cool.
In a mixer beat eggs, sugar and add in chocolate mix. The batter will be shiny. Stir in salt and vanilla. Mix in the spelt flour just until combined.
Sprinkle with chunky sea salt.
Pour the batter into the prepared pan and bake until a toothpick inserted in the centre comes out with just a few crumbs clinging to it, 25–30 minutes.
Meanwhile, heat 1/4 cup butter, 1/4 cup milk, 1/4 cup sugar and stir over heat until it thickens slightly.
Let the brownies cool- poke with a butter knife and gently put the butter, milk, sugar mixture into the knife slats.
Cut and enjoy!