Bring 1.5 liters of Cow's Milk to a gentle boil in a heavy-bottomed pan, stirring occasionally to prevent scorching.
Turn off the heat and slowly add 2–3 tablespoons of Lemon Juice while stirring gently; the milk will begin to curdle. Let it sit for a minute, then strain the curds (chenna) through a fine cloth or cheesecloth, reserving the whey.
Rinse the strained curds under cold running water to remove any lemony tang, then squeeze out excess liquid and hang or press the cloth for 20–30 minutes to drain thoroughly.
Transfer the drained curds to a clean surface and knead vigorously for 6–8 minutes until smooth and pliable; divide into 12–16 equal portions and gently roll each into a smooth ball, then flatten slightly into thick discs.
Make a light sugar syrup by combining 1 cup of Sugar and 3 cups of Water in a wide pan; bring to a simmer until the sugar dissolves.
Carefully drop the chenna discs into the simmering syrup (do not overcrowd). Cover and poach them over medium-low heat for 8–10 minutes until they expand and feel light; remove with a slotted spoon and let cool in a bowl of cold water for a few minutes, then gently transfer to a plate.
To prepare the rabri (flavored reduced milk), pour 1 liter of Cow's Milk into a wide, heavy pan and simmer gently, stirring and scraping the sides to collect cream, until reduced by about one-third and slightly thickened.
Stir in a pinch of Saffron (soaked in a tablespoon of warm milk if desired), 1/4–1/2 teaspoon of Ground Cardamom, and 3–4 tablespoons of Sugar to taste; simmer briefly to dissolve and incorporate.
Remove the rabri from heat and stir in 1–2 teaspoons of Rose Water for a floral finish. Cool slightly.
Gently squeeze any excess syrup from the chenna discs, then place them in a shallow dish and pour the warm (or cooled) rabri over them so they are fully submerged. Chill for at least 2 hours to allow flavours to meld.
Before serving, garnish with chopped Pistachios and slivered Almonds. Serve chilled.
