For the chicken: Put a large skillet over medium-high heat and add the grapeseed oil. When it starts to get hot, add the garlic, ginger and onions, and cook until the onions are golden, about 4 minutes. Add the tomato paste, cumin, garam masala, brown sugar, chili flakes, salt and turmeric, and cook for 2 minutes. Add the chicken and stir well to coat. Stir in the yogurt and 1/2 cup water and cook until the chicken is done, 8 to 10 minutes. Let cool, and then shred the meat using a fork or your fingers.
For the parathas: Combine the flour, coriander, cumin, salt and 1/2 to 1 cup water in a large bowl and mix with your hands until it begins to form a ball. If it there is excess flour and it seems dry, add more water. Knead until it has a smooth consistency, like pizza dough. The dough should be soft and smooth. Divide the dough into 12 equal pieces and roll each into a smooth ball. Pat a ball into a disc and then place on a floured surface and roll it out into a very thin circle, about 6 inches in diameter, like a tortilla.
Place 1/2 cup butter chicken filling onto the disc, and then roll out a second ball and place it over the butter chicken. Lightly go over the paratha with the rolling pin to seal it, taking care not to push the filling out of the edges. Continue to roll and fill the remaining discs.
Place a nonstick pan over medium-low heat and gently place a paratha into it. Brush the top with a little of the flaxseed oil and let it cook until the dough begins to bubble and turn brown, about 1 minute. Flip the paratha, oil it lightly and continue to cook it until it's golden and crispy. Brush the top with a little more of the oil. Repeat the process for the remaining parathas. Serve with Sweet Tomato Chutney.
Put the sugar, salt, cardamom and tomatoes into a saucepan over high heat and bring to a boil.
Reduce the heat to low and simmer gently until it has reduced and thickened significantly, 45 minutes to 1 hour. Let cool slightly and stir in the cilantro and onions.