Prepare the cheese: Remove the halloumi from its packaging, rinse briefly and pat very dry with paper towels. Slice into 8 even slices, about 1/3–1/2 inch (8–12 mm) thick. Drying the surface removes excess moisture so the cheese will sear instead of steam — that gives you a golden, textural crust.

Warm your pan and brown the butter: Use a 10–12-inch stainless-steel or nonstick skillet and heat it over medium heat. Add the unsalted butter and let it melt and foam, swirling occasionally. Watch closely — within 2–3 minutes the milk solids will begin to brown and you'll smell a nutty aroma. Remove the pan from the heat briefly when the solids are golden (this creates brown butter, which adds a deep, toasty flavor that pairs beautifully with caramelized sugar). Reserve about 1 tbsp of the brown butter in a small bowl for finishing.

Return the pan to medium-high to sear the cheese: If your pan looks dry, add the optional 1 tsp oil (it raises the smoke point). Once hot, add the halloumi slices in a single layer — don't crowd the pan. Sear undisturbed 2–3 minutes until a deep golden-brown crust forms (this Maillard reaction builds savory depth and prevents the cheese from becoming rubbery). Flip and sear the other side another 1–2 minutes.

Caramelize the sugar onto the cheese: Push the cheese to one side of the pan (or transfer to a clean plate and keep pan hot). Sprinkle 1/2 tbsp sugar evenly over each slice (about 1 tsp / slice). Over medium heat, let the sugar sit undisturbed for 30–90 seconds until it melts and starts to bubble and amber — you’re making a quick pan caramel that will form a crisp, sweet shell. Watch closely: sugar goes from caramel to burnt very quickly.

Coat and finish the slices: As the sugar liquefies and becomes golden, carefully tilt the pan and spoon a little of the hot brown butter over the melting sugar to help it gloss and flavor the crust (use oven mitt and a spoon). Quickly return each slice to the sugar-glazed surface for 15–20 seconds so the caramel adheres, then transfer to a wire rack or warm plate. The short contact keeps the crust crisp while keeping the interior pleasantly yielding.

Spice and season: In the small bowl with the reserved brown butter stir in the ground cinnamon. Spoon a teaspoon of the spiced brown butter over each slice, then finish with a delicate flake of sea salt on top of the caramel. The salt brightens the flavors and balances the sweetness; the cinnamon adds warm aromatic notes.

Rest briefly and serve warm: Let the cheese rest 1–2 minutes — the caramel will set slightly but remain crackly. Serve immediately while warm and the texture contrast (crispy caramel exterior, warm squeaky interior) is at its best.

Safety and cleanup tip: If any caramelized sugar sticks to the pan, deglaze while warm with a splash of hot water (stand back — it will steam). This makes cleanup much easier and prevents burnt sugar residue.