Prepare the Ramekins

1. Preheat the Oven: Preheat your oven to 425°F (220°C).
2. Grease Ramekins: Generously grease four ramekins with butter and place them on a baking sheet.

Melt Chocolate and Butter

1. Melt Together: In a microwave-safe bowl, combine the unsalted butter and semi-sweet chocolate chips. Microwave in 30-second intervals, stirring until smooth and fully melted.

Mix the Batter

1. Combine Sugar and Pumpkin: In a mixing bowl, whisk together the granulated sugar and pumpkin puree until well combined.
2. Add Eggs and Yolks: Incorporate the eggs, egg yolks, and vanilla extract into the pumpkin mixture, whisking until smooth.
3. Stir in Chocolate: Gradually mix the melted chocolate and butter into the pumpkin mixture until fully combined.
4. Fold in Dry Ingredients: Gently fold in the flour, pumpkin pie spice, and salt until just combined.

Fill Ramekins

1. Add Caramel: Spoon about 2 tablespoons of batter into the bottom of each greased ramekin.
2. Add Caramel Filling: Place about 1 tablespoon of caramel sauce in the center of each ramekin, then top with the remaining batter, covering the caramel.

Bake the Lava Cakes

1. Bake: Bake in the preheated oven for 12-14 minutes, or until the edges are firm but the center is still slightly soft.
2. Cool Slightly: Remove from the oven and let the cakes cool for 1 minute.

Serve

1. Invert and Serve: Carefully invert each ramekin onto a serving plate. Gently lift the ramekin to reveal the molten lava cake.
2. Garnish: Drizzle with extra caramel sauce and serve warm, preferably with a scoop of vanilla ice cream.