Apart from the popular Ghewar, if there's any dessert synonymous with Hariyali Teej, then it would be Rabri. This velvety sweet is popular all around India, especially in Northern states, and is essentially a milk-based dessert. Here's a classic yet easy recipe to try:
1 liter full-fat milk
1/2 cup sugar
1/2 teaspoon cardamom powder
2 tablespoons chopped nuts (almonds, pistachios)
A few saffron strands (optional)
Boil milk in a broad, heavy-bottomed pan over medium heat, stirring constantly.
After it reaches a boil, simmer it until it reduces by half, stirring now and again to avoid burning. Scrape down the edges often to collect the cream and return it to the milk.
Stir in nuts, cardamom powder, and saffron (if using) and mix thoroughly. Keep cooking until the milk becomes creamy and thick.
After letting it cool, refrigerate. Serve cold, with more nuts on top.