Granted this is more work than the OP’s recipe, but it is worth it.
6 cloves garlic
Bottom half of a stalk of lemon grass
1 tsp. Galanga, minced fresh or frozen galangal ginger, or substitute with 1/2 tsp.
ground dried galangal
2 tsp. minced cilantro roots, or substitute with bottom stems
2 tsp. coriander seeds
1/2 tsp. cumin seeds
5 dried red chillies
1/4 tsp. freshly ground nutmeg
1/4 tsp. ground cinnamon
1/4 tsp. ground mace
1/2 to 1 tsp. shrimp paste
1/2 cup unsalted roasted peanuts
1 1/2 to 2 cups (or 1 14-oz can) coconut milk
1-2 Tbs. fish sauce to taste
1-2 Tbs. palm or coconut sugar, to taste
1 Tbs. tamarind water – dissolve a 1 tsp. chunk of wet tamarind in 1-2 Tbs. water
Cut and discard the root tip of the garlic cloves but leave the skin on. Do likewise with the shallots. Place both on a tray in a toaster oven (or oven) and roast at 400 to 450 degrees until softened (about 10-15 minutes for garlic and 20-30 minutes for shallots, depending on the size of the cloves and heads).
In the meantime, trim and discard the bottom tip and loose outer layer(s) of the lemon grass. Cut the stalk into very thin rounds, then chop. Mince the galangal ginger and cilantro roots (or stems).
In a small dry pan, toast the coriander seeds over medium heat until they are aromatic and dark brown, stirring frequently. Do likewise with the cumin seeds. Follow with the dried red chilies, stirring constantly until they turn a dark red color and are slightly charred. Grind the toasted ingredients in a clean coffee grinder to a fine powder.
Using a heavy mortar and pestle, pound the lemon grass, galangal and cilantro roots (stems) until they are reduced to a paste. Peel the roasted garlic and shallots and mashed in with the mixture until well blended. Then add the ground toasted ingredients, plus the nutmeg, cinnamon, mace and shrimp paste. Pound to make a well-blended paste.
Grind the peanuts in a clean coffee grinder or blender as finely as possible. Heat 2/3 cup of the thickest cream from the top of a can of coconut milk in a saucepan over medium-high heat. Reduce a few minutes until thick and bubbly. Fry the spice mixture in the cream, stirring frequently, until it is well mixed with the cream and has fully released its aromas and flavors (3-5 minutes).
Add half the remaining milk and the ground peanuts. Bring to a boil, then reduce heat to low and simmer 10-12 minutes, stirring well to blend the ingredients. Add more coconut milk as needed to constitute a creamy sauce the consistency of pancake batter. Season to taste with fish sauce, palm sugar and tamarind water to the desired combination of salty and sweet, with a subtle tangy flavor in the background.
Simmer a few minutes more, then transfer to a sauce dish and cool to room temperature before serving with your favorite grilled meats, fish, tofu and vegetables.