Chop up your ingredients, if large.
These bars hold together best when the ingredients are quite small. If using almonds, you’ll want to either start with pre-sliced almonds, or chop them up in the food processor or by hand (same goes for all nuts). It’s easy to throw all of your mix-ins into the food processor and blitz a few times.

Press the mixture down as firmly as evenly as possible.
Air pockets will cause problems. Use a sturdy, flat-bottomed jar to make sure the mixture is pressed down completely. You might then press down with your hands to ensure it’s not trying to sneak up the sides or corners.

Let the mixture rest for one hour or longer before using.
The oats need some time to soak up the moisture in the nut butter and sweetener. Chill the mixture for at least one hour (or as long as a day) before slicing.