Preheat your oven to 375°F (190°C). This temperature is perfect for allowing the sauce to caramelize slowly without burning, giving the kielbasa a glossy, flavorful coating.

Cut the kielbasa into 1-inch pieces. For a fun and flavorful twist, you can use the hasselback slicing method: Place each kielbasa piece between two chopsticks or skewers, then slice into 1/4-inch sections without cutting all the way through. The chopsticks act as a barrier, ensuring the knife doesn’t cut through completely. This creates three connected sections in each piece, which allows more sauce to seep in during baking.

Place the sliced kielbasa in a baking dish large enough to hold them in a single layer. Add the brown sugar, ketchup, and prepared horseradish directly to the dish. Stir everything together until the sausage is evenly coated. The mixture will start off loose, but it will thicken beautifully as it cooks.

Place the dish in the preheated oven and bake for 60–90 minutes, stirring every 20 minutes to ensure even caramelization. The exact cook time will depend on how crisp and sticky you like your kielbasa—60 minutes yields tender, saucy bites, while 90 minutes gives a more concentrated, chewy glaze with browned edges.

Once the kielbasa is glazed and caramelized to your liking, remove from the oven. Serve them hot straight from the baking dish or transfer to a platter with toothpicks for easy grabbing.