Set a square of parchment paper over a medium-sized plate. Lightly butter or coat the parchment with spray oil. In a medium, dry saucepan over medium-high heat, melt the sugar, stirring if necessary to break up large chunks. By the time it’s fully melted, it should be a nice copper color. If not, cook until it is. Remove from heat and stir in butter. It may not fully incorporate but do your best. Stir in cream and salt, return to stove and bring back to a simmer. Cook until it’s a shade darker. Pour onto parchment-covered plate and transfer to freezer. Freeze until solidified, 20-40 minutes.

Heat oven to 350°F. Line an 8x8-inch square baking pan with parchment, extending it up two sides. Butter or spray the parchment.

In a medium heatproof bowl over gently simmering water, melt chocolate and butter together until only a couple of unmelted bits remain. Off the heat, stir until smooth and fully melted. (Microwave option: In 30-second bursts, stirring between each).

Whisk in sugar, then eggs one at a time, then vanilla and salt. Stir in flour with a spoon or flexible spatula.

When caramel is firm, remove it from the freezer and chop into rough 1-inch squares. Gently fold most of the caramel bits into batter. Scrape batter into prepared pan, spreading until mostly even. Scatter remaining caramel bits on top.

Bake in heated oven for 30 minutes, until a toothpick inserted into the center comes out clean. Cool thoroughly (this can be hastened in the freezer for cleaner cuts), then cut into squares or desired shapes.