Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Wash the kale thoroughly and dry it completely using a salad spinner or paper towels to ensure the leaves become crunchy during roasting.
Tear the kale leaves into bite-sized pieces, making sure to discard the tough woody stems.
In a large mixing bowl, toss the kale pieces with olive oil, minced garlic, sea salt, black pepper, and red pepper flakes until every leaf is evenly coated.
Spread the kale in a single layer on the prepared baking sheet and roast for 10-12 minutes, tossing halfway through, until the edges are crispy and golden.
While the kale is roasting, grill the chicken breast over medium-high heat for approximately 6-7 minutes per side until the internal temperature reaches 165°F.
Slice the grilled chicken and serve it immediately alongside the roasted kale, finishing the dish with a fresh squeeze of lemon juice and a sprinkle of parmesan cheese.