In a small saucepan, melt the butter over medium heat. Add the brown sugar and stir constantly until it’s melted and smooth. Be careful not to burn the sugar.
Add the chopped pecans (or walnuts) and stir to coat them evenly in the caramel. Cook for another minute or two, until the nuts are toasted and fragrant.
Pour the praline mixture onto a parchment-lined baking sheet and spread it into a thin layer. Let it cool completely. Once cooled, break the praline into small pieces or crush it with a rolling pin. You want a mix of larger and smaller pieces for the best texture.
In a jar or container with a lid, combine the rolled oats, milk, Greek yogurt (or plant-based yogurt alternative), maple syrup (or honey), vanilla extract, and a pinch of salt. Stir well to combine.
Add the chopped chestnuts to the oat mixture and stir gently to distribute them evenly throughout. Reserve some chopped chestnuts for topping later.
Sprinkle half of the praline crunch over the oat mixture. This will infuse the oats with that delicious praline flavor as they soak overnight. Reserve the remaining praline for topping before serving.
Seal the jar or container tightly with a lid and refrigerate for at least 6 hours, or preferably overnight.
In the morning, give the overnight oats a good stir. If they seem too thick, add a splash of milk to loosen them up. Top with the remaining praline crunch, chopped chestnuts, and a drizzle of maple syrup (optional).
