Heat 2 tbsp olive oil in a large pot over medium heat for 2 minutes until shimmering. Add chopped onion and cook for 5 minutes, stirring occasionally, until translucent. Stir in minced garlic and cook for 1 minute until fragrant.
Pour in 4 cups vegetable broth and bring to a boil.
Add 1 lb. frozen peas and return to a boil.
Reduce heat to low and simmer for 3 minutes until peas are bright green and tender.
Carefully transfer the hot mixture to a blender. Blend on high speed for 2 minutes until completely smooth.
Add 1/2 cup heavy cream, 1 tsp salt, and 1/2 tsp black pepper to the blender. Blend for 30 seconds until fully incorporated. Taste and adjust seasoning if needed.
Ladle soup into bowls and top with mint leaves and crumbled feta.