For the butter solids: Combine the milk powder and butter in a sauce pot and cook over high heat. The heat will brown the milk powder, creating an amplified brown butter flavor. Butter on its own will not provide much brown butter flavor due to the small amount of milk solids in it. If more milk solids are added, then the resulting mixture will have more of that flavor.
Cool in a hotel pan at room temperature.
For the panna cotta: Combine the cream, sugar, and brown butter solids in a 960 mL/1 qt sauce pot and bring to a simmer to dissolve the sugar and brown butter solids. Pass through a fine-mesh sieve.
Add the bloomed gelatin and stir until it has dissolved.
Portion 20g/.70oz into the desired bowl.
Let set uncovered in the refrigerator for at least 3 hours before service. Once it has set, cover loosely with plastic wrap. Discard after 2 days.