Bring 1 liter of whole milk to a boil in a medium pot over medium-high heat, stirring occasionally. Once boiling, turn off the heat and let the milk cool for 2 minutes. Gradually add the diluted lemon juice, one tablespoon at a time, stirring gently in a single direction. Stop adding juice as soon as the milk curdles completely, leaving a clear, greenish-blue liquid whey.

Pour the curdled milk into a colander lined with a clean cheesecloth to catch the curd. Rinse the curd under cold running water for 1 minute to cool it down and wash away any sour lemon taste. Gather the corners of the cloth, squeeze gently to expel excess water, and hang the bag over a sink or colander to drain passively for 45 minutes.

While the curd is draining, combine the other 1 liter of whole milk in a heavy-bottomed pan and bring to a boil. Lower the heat and simmer for 35 minutes, stirring frequently and scraping down the sides of the pan, until the milk is reduced by half. Add 100 grams of sugar, the steeped saffron, and cardamom powder. Simmer for 2 minutes until the sugar is dissolved, then turn off the heat and keep the rabri warm.

Remove the drained curd from the cheesecloth and place it on a clean, flat work surface. The curd should feel soft and moist but not wet. Add 1 teaspoon of cornstarch. Use the heel of your palm to rub and knead the mixture for 5 to 7 minutes until it becomes a smooth, cohesive dough that no longer sticks to your hands.

Divide the kneaded dough into 12 equal portions. Roll each portion gently between your palms to form a smooth ball, then press lightly to flatten it into a disc about 3 cm in diameter. Ensure there are no cracks along the edges. If cracks form, knead that portion briefly before reshaping.

In a wide, deep pot, heat 150 grams of sugar and 1 liter of water over high heat. Bring the syrup to a rapid rolling boil. Gently slide the shaped discs into the boiling syrup. Cover the pot tightly with a lid and cook over medium-high heat for 15 minutes. The discs will expand to double their original size.

Turn off the heat and let the discs cool in the syrup for 5 minutes. Use a slotted spoon to lift a disc, then gently press it between two flat spoons to squeeze out the excess sugar syrup. Drop the warm, squeezed disc directly into the warm rabri. Repeat for all discs. Let the dessert cool to room temperature, then cover and refrigerate for at least 3 hours before serving. Garnish with almonds and pistachios.