Preheat your oven to 425°F. While it heats, prepare the radishes by halving or quartering them into ½-inch pieces—this uniform sizing ensures even roasting. Mince the garlic cloves finely; this prevents them from burning when added later in the cooking process.
In a large bowl, combine the prepared radishes with the ghee, salt, black pepper, dried parsley, and dried thyme. Toss everything together until the radishes are evenly coated with the fat and seasonings. I like using ghee here because it creates a richer, more buttery roasting crust than neutral oils.
Spread the coated radishes in a single even layer on a baking sheet or in a roasting pan. Bake for 10 minutes at 425°F. This initial roast begins to soften the radishes and allows them to start developing color and caramelization.
Remove the pan from the oven and stir in the minced garlic from Step 1, distributing it evenly among the radishes. Return to the oven and roast for another 10-15 minutes until the radishes are tender and caramelized at the edges, with the garlic fragrant but not browned.
Remove the roasted radishes from the oven and drizzle with the lemon juice, stirring gently to distribute. Transfer to a serving dish and dollop with ranch dressing. I find that the lemon juice adds brightness that cuts through the richness of the ghee and prevents the dish from feeling too heavy. Serve immediately while still warm.