Meanwhile, heat a large drizzle of oil in a large pan over medium-high heat. Add chopped kale and tomato; season with half the Tuscan Heat Spice (all for 4 servings), ¼ tsp salt (½ tsp for 4), and a pinch of pepper. Cook, stirring occasionally, until tender, 5-7 minutes.
Add garlic; cook, stirring, until fragrant, 30 seconds.
Stir in stock concentrate and ¼ cup reserved pasta cooking water (1⁄3 cup for 4); cook, stirring, until sauce has thickened, 1-2 minutes.
Remove from heat; stir in cream cheese, 2 TBSP butter (4 TBSP for 4), and a squeeze of lemon juice until melted and combined. TIP: If sauce seems too thick, stir in more reserved pasta cooking water a splash at a time.
While veggies cook, pat chicken dry with paper towels; season all over with salt and pepper. Heat a drizzle of oil in a medium pan over medium-high heat. Add chicken and cook until browned and cooked through, 3-5 minutes per side. Transfer to a cutting board to rest.