Preheat the oven to 350 degrees F (175 degrees C).
Place acorn squash halves, cut-sides up, on a baking sheet. Place 1 teaspoon coconut oil and 1 teaspoon brown sugar in the cavity of each half. Season with salt and pepper.
Roast in the preheated oven until tender when pierced with a fork, 40 to 60 minutes. Remove from the oven and set aside to cool.
While cooling, heat remaining 2 teaspoons coconut oil in a large pot over medium-low heat. Add onion and saute until soft and caramelized, 7 to 10 minutes. Add garlic, curry paste, ginger, and a pinch of salt; stir to incorporate and cook, stirring occasionally, until fragrant, about 5 minutes. Pour in vegetable stock and cook until heated through, 3 to 5 minutes.
Scoop the squash flesh out of the skins and place it into the pot. Puree soup with an immersion blender until smooth.
Stir in coconut milk and lime juice; season with salt and pepper. Heat until completely warm throughout, about 3 minutes. Ladle into bowls and garnish with roasted pumpkin seeds.