Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Peel and cube the sweet potato into 1-inch pieces, then toss them with 0.25 tbsp of olive oil, a pinch of sea salt, and black pepper.
Spread the sweet potatoes on the baking sheet and roast for 20-25 minutes until tender and slightly caramelized.
While potatoes roast, season the chicken thighs evenly with sea salt, black pepper, and dried oregano.
Heat the remaining 0.5 tbsp of olive oil in a large skillet over medium-high heat.
Place the chicken thighs in the skillet and sear for 5-7 minutes per side until golden brown and the internal temperature reaches 165°F.
During the last 2 minutes of chicken cooking, add the minced garlic to the pan and stir until fragrant.
Remove the chicken from the pan and set aside; immediately add the fresh spinach to the hot skillet.
Sauté the spinach for 1-2 minutes until just wilted, using the residual heat and garlic in the pan.
Plate the seared chicken thighs with the roasted sweet potatoes and sautéed spinach.