Add pine nuts to a small skillet. Toast over med-high heat, stirring often to avoid burning. Once they begin to become fragrant and lightly browned they are ready, about 5-6 minutes. Remove from heat. 

In a medium skillet cook the diced pancetta until crispy and cooked through. Drain onto a paper towel lined plate. Wipe out skillet and set aside to use in the last step.

Add trimmed and washed green beans to a large saucepan. Fill about 2/3 full with water and bring to a boil over med-high heat. Reduce heat to med-low and simmer for about 3-5 minutes. Drain and place beans into an ice water bath to stop the cooking, this will help keep their color and a slight crunch.

Add the cooked beans, cooked pancetta, and toasted pine nuts back into the medium skillet over med-low heat. Stir in butter, salt and pepper. Heat through until butter is melted and beans are warmed through, serve immediately.