Prepare and add the carrots to the slow cooker.: When you slice the carrots into 1/2 inch pieces you should notice a clean, slightly sweet aroma and a crisp snap when bitten raw. Even sizing helps the heat penetrate uniformly so every piece becomes tender at the same time. If pieces are in inconsistent sizes, some will overcook while others remain firm, so take the extra few minutes to slice carefully. The visual cue to look for when they are ready is a bright color that looks slightly intensified, not a dull or mushy appearance.
In a medium bowl, whisk together the melted butter with the rest of the ingredients.: As you whisk the glossy unsalted butter with brown sugar , balsamic reduction , soy sauce , and maple syrup you should hear a faint rustle of the whisk and see the sugar beginning to dissolve. This emulsification helps create a cohesive glaze that coats the carrots evenly, which is why I always whisk until the sugar looks incorporated. A mistake people make is not dissolving the sugar enough, which can result in grainy spots in the final glaze.
Pour the sauce mixture on top of the carrots and toss to combine.: When you pour the sauce over the carrots the aroma will momentarily brighten as the acids and sugars mingle. Tossing ensures every piece is coated, which promotes even caramelization and infusion of flavors. Use a gentle motion to avoid breaking the carrots . If you skip the toss and leave pockets uncoated, some pieces may cook blandly while others become syrupy.
Cook on HIGH for 180 minutes or until carrots are tender.: Over the long cook you will notice the kitchen filling with warm, sweet scents from the brown sugar and maple syrup , and the carrots will soften to a tender bite. The low and steady heat allows the glaze to concentrate and settle into the vegetables, creating that irresistible silkiness. Avoid opening the lid repeatedly as it cools the cooker and lengthens cooking time; only check near the end to test tenderness with a fork.
To thicken the glaze, remove uncovered on HIGH for an additional 20-25 minutes. Or mix 1 tablespoon of cornstarch with 3 tablespoons of water and add to the mixture, cook on HIGH for an additional 15 minutes.: As the glaze reduces uncovered you should see the liquid bubble gently and the sauce become syrupy, coating the carrots in a glossy sheen. The uncovered finish intensifies the caramel notes and gives a lovely tacky texture. If you choose the cornstarch slurry, whisk it thoroughly so it disperses without lumps and yields a smooth, clingy glaze. A frequent misstep is adding undissolved cornstarch which can create cloudy, pasty spots.
Sprinkle with parsley and serve.: The final sprinkle of chopped parsley delivers a bright green pop and a fresh herbal scent against the sweet, warm glaze. Visually the contrast is pleasing, and on the palate the herb cuts through some richness, keeping the dish balanced. Plate while warm for the best texture, since the glaze sets as it cools and can tighten the mouthfeel if left too long.
