Toast 2 Tbsp pine nuts in a large dry skillet over medium heat for 1-2 minutes until fragrant, watching closely to prevent burning.
Remove toasted pine nuts to a bowl and set aside.
Add 1 1/2 lbs trimmed green beans and 1/2 cup water to the same skillet and bring to a simmer over medium-high heat.
Cover and cook for 3 minutes until beans are slightly tender.
Remove lid and stir until water evaporates, 3-4 minutes, until beans are crisp-tender.
Make a well in the center and add 1 Tbsp olive oil and 1 Tbsp unsalted butter until butter melts.
Add 1 medium thinly sliced shallot to the well and sauté until soft and browning on edges, 3-4 minutes.
Add 3 minced garlic cloves and cook until fragrant, 30 seconds.
Stir everything together to coat beans with shallot-garlic mixture.
Remove from heat and add 1/2 tsp red pepper flakes, 1 1/2 tsp lemon zest, lemon juice to taste, kosher salt, and black pepper.
Toss together, taste, and adjust seasonings as needed.
Transfer to serving dish and top with toasted pine nuts.
Serve immediately while beans are still crisp.