Either line your slow cooker with a disposable liner or spray generously with nonstick spray.Drain the sweet potatoes. Add the sweet potatoes, butter, white sugar, pinch of salt, brown sugar, and orange juice in the slow cooker.In a small bowl, lightly beat the eggs with a fork. Pour in the lightly beaten eggs, vanilla extract, and milk into the slow cooker.Beat until completely smooth. (Alternatively, you can beat all of these ingredients in a different bowl).Smooth the mixture with a spatula.In a small bowl, stir together all of the topping ingredients. Spread the topping mixture evenly on top of the sweet potatoes.Cover the crockpot and cook on high for 2 and 1/2 to 4 hours depending on how hot your slow cooker cooks.