Pour cream into a nonstick pan placed over medium high heat and reduce without stirring. When it starts turning yellow gently stir and scrape the bottom of the pan to prevent the milk solids burning.
Remove from heat when the cream is reduced to a creamy texture and add water back in so the final weight is again 200g.
Add to a saucepan with toasted skimmed milk powder, dextrose (if using) and glucose to the pot and heat to 75C. Meanwhile whisk the brown sugar with the egg yolks until light and airy, pour the hot cream over the yolks to temper, then return the mixture to the saucepan. Cook while stirring continuously until the custard reaches 82C on an instant read thermometer.
Remove from heat and leave to cool to 60C before mixing with buttermilk. (Buttermilk splits and curdles when heated, so be careful with your temperatures). Strain and transfer to a bowl placed over an ice bath to cool down rapidly.
Season to taste with salt and refrigerate overnight before churning in ice cream maker according to manufacturers instructions.
