Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Remove the tough stems from the kale and tear the leaves into bite-sized pieces. Place them on the baking sheet, drizzle with half of the olive oil and a pinch of sea salt, then toss to coat.
Roast the kale in the oven for 8 to 10 minutes, or until the edges are golden and crisp, then set aside.
While the kale roasts, season the chicken breast on both sides with the garlic powder, dried oregano, sea salt, and black pepper.
Heat the remaining olive oil in a large skillet over medium-high heat. Once hot, add the chicken breast and sear for 5 to 7 minutes per side until the internal temperature reaches 165°F.
In the last 2 minutes of cooking the chicken, move the breast to the side of the pan and add the minced garlic and fresh spinach. Sauté until the spinach is just wilted.
Remove the skillet from the heat and squeeze the fresh lemon juice over the chicken and sautéed spinach.
To serve, plate the roasted kale as a base, top with the wilted spinach, and place the sliced lemon-herb chicken on top.