In a big mixing bowl, mix the all-purpose flour, ground cardamom, and salt. Set it aside.
In another bowl, mix the coconut milk, yeast, and sugar until it's well combined. Let it sit for 10 minutes.
Make a hole in the flour mix. Crack in the eggs, then pour in the melted butter. Whisk it well to break the eggs. Slowly stir in the coconut milk mixture with a wooden spoon. Keep stirring until you have a soft, elastic dough. This takes about 5-6 minutes with a stand mixer or 15 minutes if you're kneading by hand. If the dough is too sticky, add more flour.
Grease a big bowl and put the dough in it. Cover it with a clean, damp cloth or plastic wrap. Let it sit at room temperature for about an hour, or until it doubles in size.
Line one baking sheet with a paper towel and another with parchment paper.
Deflate the dough and knead it for about a minute. If it's too sticky, add 2 tablespoons of flour. Divide the dough in half. Roll it on a floured surface into a large rectangle, about ½-1 inch thick. Cut it into rolls, squares, or triangles, about 2x2 inches. Put the shaped dough on the parchment-lined baking sheet and cover it with a kitchen towel.
Heat vegetable oil in a deep skillet, wok, or large Dutch oven over medium-low heat until it reaches 350°F.
Slowly dip in the Mandazi pieces, making sure not to overcrowd the pan. Fry until golden brown on both sides, about 2-3 minutes per side. Repeat until you run out of dough. Make sure the oil is hot enough for that crispy exterior.
Take the Mandazi out of the oil using a slotted spoon and put them on the paper towel-lined baking sheet to get rid of any extra oil.
Put the Nutella® in a piping bag with a long tip. Once the Mandazi has cooled a bit, use a wooden skewer, toothpick, or metal tip to poke a hole in each one and fill it with Nutella®. Sprinkle with powdered sugar if you like. Serve warm with Chai tea if you want to enjoy a delightful treat!