In a large skillet, melt butter over medium-high heat. Add apples and ginger; cook and stir until apples soften and begin to caramelize, 3-5 minutes. Stir in pistachios and Dijon mustard. Reduce heat; simmer 5 minutes, stirring occasionally., Pour two-thirds of apple mixture over spinach. Add spoonfuls of ricotta cheese; top with remaining apple mixture. Drizzle with honey. Add fresh pepper to taste.