I always start by patting the turkey breast completely dry with paper towels, inside and out. This step matters more than people think, because any extra moisture stops the skin from crisping later. I take my time here rather than rushing it.
Next, I place the halved garlic head, quartered onion, and thyme sprigs face-down in the bottom of the slow cooker. This little bed does double duty: it flavors the meat and keeps the turkey breast elevated so it doesn't sit directly in its own juices.
I rub softened butter under and over the skin, then season generously with salt, pepper, and paprika. I set the turkey breast on top of the aromatics, skin-side up, so it rests above the vegetables rather than in them.
I never add water or broth at this stage. The turkey releases its own juices as it cooks low and slow, which is exactly what keeps it so moist. I cover the slow cooker and set it to LOW for 5 to 6 hours for a 4 lb breast.
Around the 4-hour mark, I start checking the internal temperature with a meat thermometer inserted into the thickest part. I'm looking for 165°F (74°C), and I like to start checking early rather than guessing.
Once it's done, I carefully lift the turkey out onto a baking sheet and let it rest for about 20 minutes. I never leave it in the slow cooker on the Warm setting, since that can overcook the meat and dry it out.
After resting, I brush the skin with a little olive oil and slide it under the broiler for a few minutes until it turns golden and crackly. I keep a close eye on it since broilers work fast and can go from golden to burnt quickly.
While the skin crisps, I strain the leftover juices from the slow cooker into a saucepan. If I'm short of 2 cups of liquid, I top it up with chicken broth, then simmer it down into a rich, ready-made gravy.
Finally, I carve the turkey breast against the grain into even slices and arrange them on a serving platter. I spoon that warm gravy right over the top just before bringing it to the table.