Shrimp Pasta with Sun-Dried Tomatoes

Ingredients (14)

• 12 ounces long fusilli , or other long noodle of choice
• 4 tablespoons butter , divided
• 1 tablespoon extra virgin olive oil
• 1 pound shrimp , peeled, cleaned, and deveined (leave the tails on if you like)
• 1/2 teaspoon kosher salt , plus more for salting the pasta water
• freshly ground black pepper
• 2 tablespoons shallot , minced
• 2 large cloves garlic , minced or pressed
• 1/4 teaspoon red pepper flakes
• 1/4 cup tomato paste
• 1/2 cup sun dried tomatoes in oil , drained and chopped (a 6-ounce jar)
• 1 cup mascarpone , (an 8-ounce container)
• 1 cup reserved pasta water
• 1/2 cup fresh tarragon , roughly chopped, plus more for serving (you could also use fresh basil if you prefer)