Heat up the chicken in a skillet over medium heat, and season with salt, pepper and oregano. Continue cooking until the chicken is golden brown and no longer pink inside, about 12 minutes on each side. Remove from the pan and set aside.
Melt the butter in another skillet over medium heat. Stir in garlic and cook for about 1 minute. Add the cherry tomatoes and season with salt and pepper. Cook until tomatoes begin to burst, and then add spinach. Cook until the spinach leaves are soft.
Stir in the coconut milk and Parmesan cheese. Reduce the heat to low and simmer for about 3 minutes, until the sauce is slightly reduced. Add chicken to pan and cook for 5 to 7 minutes. Remove from heat, squeeze the lemon over the chicken and serve.