Preheat the oven to 325 degrees. Prepare a large baking sheet (or two small baking sheets) with parchment paper.

Toss oats with melted butter until well coated. Spread oats on the baking sheet.

Toast in the oven, stirring every 5 minutes, for 15 minutes total or until golden. Remove from the oven and cool.

In a medium saucepan over medium heat, stir together the brown sugar, maple syrup, water, vanilla extract, and nut butter. Stir until the sugar is melted and thoroughly combined. Bring to a boil and immediately remove from heat.

Meanwhile, in a large bowl, stir together the cooled oats, cereal or pretzels, ground flax, nuts, and dried fruit or morsels.

Pour the sugar syrup over the dry ingredients and stir until completely combined. You might need to use greased hands to completely mix.

Transfer the granola to the prepared baking sheet. Press tightly in a level rectangle.

Bake in the 325 degree oven for 25 minutes. 

For best results, lift the granola from the baking sheet to a curing board using the parchment paper. Cut the granola bars while warm using a sawing motion with the knife. Trying to force the knife through the granola will cause it to crumble.