Dice sweet potatoes into 1" pieces and place them in a bowl. In a separate bowl, combine olive oil, garlic, oregano, pepper, and salt, then pour mixture over the sweet potatoes and stir to combine.
Line a baking sheet with foil OR spray with nonstick spray and pour potatoes onto baking sheet. Bake potatoes for 25-30 minutes, or until soft.
While potatoes are roasting, make the brown butter: Place butter into a small saucepan and heat over medium-low. The butter will melt, and within a few minutes, it will start to bubble. After it's done bubbling, it will quickly change to a golden-brown color, which is when you know the butter is done. If you leave it on too long, it will burn, so make sure to keep your eyes on it!
Pour brown butter over the roasted potatoes and enjoy!