You have two options for cooking the green beans: if you want to keep them nice and green, boil them in salted water for about 2 minutes, then drain them and add to an ice bath. If this is too many steps for you, just add the green beans to your skillet with a couple tablespoons of water and cook over medium, covered, for about 5 minutes. Either way, set green beans aside while you make the sauce
In a large skillet, over medium-low heat, add 1/2 tbsp butter, garlic and almonds. Cook until almonds are deeply browned but not burned, about 5 minutes. Remove and set aside.
Add 1 tbsp butter to same skillet along with shallots and garlic. Raise heat to medium and cook until shallots are soft and translucent, about 5 minutes.
Add browned almonds, lemon juice, 1/2 tsp kosher salt, and 2 tbsps water to sauce. Cook for another 30 seconds, then add in green beans. Increase heat to high and cook for 1-2 minutes, until green beans are heated through and coated with the sauce.
Taste and season with more with salt and pepper to your liking.