Gently mash the salted egg yolks in a small bowl until they form a coarse paste. Set aside.

In a large skillet or wok, melt the butter over medium heat. Add the minced garlic and chopped shallots, sautéing until fragrant and softened, about 2-3 minutes.

Add the chopped bird's eye chilies and cook for another minute, stirring constantly, until their aroma is released.

Pour in the coconut milk and bring the mixture to a gentle simmer. Do not let it boil vigorously.

Stir in the mashed salted egg yolks. Continue to cook over low heat, stirring and gently breaking up the yolk clumps with a spoon, until the sauce begins to thicken slightly, about 2-3 minutes.

Add the sugar and salt to taste. Remember that salted egg yolks are inherently salty, so season cautiously.

Add the prepared shrimp to the skillet. Cook, stirring gently, until the shrimp turn pink and are cooked through, about 3-5 minutes depending on their size. The sauce should coat the shrimp beautifully.

Remove from heat. Stir in most of the fresh cilantro. Serve immediately.