Curried Pumpkin and Buss Up Shut

3 cups (about 12 3/4 ounces) plus 4 tablespoons all-purpose flour, divided, plus more for dusting
2 teaspoons baking powder
1 ½ teaspoons kosher salt, plus more to taste
1 teaspoon granulated sugar
1 ¼ cups warm water (95°F to 110°F)
3 tablespoons ghee, divided, plus more for brushing
6 tablespoons unsalted butter (3 ounces), softened, divided
½ cup loosely packed fresh curry leaves (about 3/8 ounce) (from 3 curry sprigs)
2 (3-inch) cinnamon sticks
10 whole star anise (about 2 tablespoons)
2 tablespoons coriander seeds
1 tablespoon cardamom pods
½ tablespoon whole cloves
¼ cup canola oil
1 medium-size (8-ounce) yellow onion, thinly sliced lengthwise (about 1 1/2 cups)
¼ cup finely chopped peeled fresh ginger (from 1 [1 1/2-ounce] piece ginger)
¼ cup peeled and grated fresh turmeric root (from 1/2 cup [2 1/2 ounces] whole turmeric)
2 fresh habanero chiles (about 1 ounce)
2 tablespoons garam masala (preferably Spicewalla)
8 cups chopped peeled pumpkin (1- to 2-inch chunks) (from 1 small [4- to 5-pound] pumpkin)
2 cups fresh callaloo leaves (about 2 ounces), trimmed and cut into 1-inch pieces
1 tablespoon kosher salt, plus more to taste
4 cups vegetable stock
1 (14-ounce) can coconut milk, well shaken and stirred
½ cup finely chopped garlic (from 20 garlic cloves)
½ cup olive oil
¼ cup toasted pepitas
2 teaspoons grated lemon zest plus 1 teaspoon fresh lemon juice (from 1 lemon)
2 garlic cloves, grated using a Microplane (about 1 teaspoon)
¼ teaspoon kosher salt