Heat oven to 350F and butter 6 small ramekins (about 5oz each).
In a bowl, soak 150g pitted dates and 50g tamarind paste in 180mL hot water. Let steep for 10 minutes.
Blend date mixture with food processor or blender until smooth. A handheld blender works well here. In a pinch, mash well with a fork.
In a large bowl, combine 58g butter and 100g brown sugar. Beat with a mixer or whisk until fluffy, at least 3 minutes. Add 1 egg, 2 tsp vanilla extract, and date mixture. Beat for another minute until well incorporated.
Sift in 1/2 tsp baking powder, 1/2 tsp baking soda, 1/2 tsp kosher salt, and 120g flour. Beat on low speed or fold with a spatula until just combined and no streaks of flour remain.
Divide batter among prepared ramekins and bake at 350F for 20-25 minutes, until a toothpick inserted in the middle comes out clean.
While the cakes bake, prepare the sauce by combining 300mL cream, 112g butter, and 150g brown sugar in a saucepot over medium heat. Bring to a boil, stirring occasionally, then reduce heat to low and for 3 minutes, until thick and glossy. Remove from heat and stir in 2 tsp fish sauce.
When cakes are done, immediately use a toothpick or skewer to poke 10-20 holes on each cake. Spoon over a couple tablespoons of sauce on each cake. Let soak for 5 minutes.
Run a knife around the edge of each ramekin before inverting onto a serving plate. Top with additional sauce and ice cream, then serve.
