Preheat your oven to 250°F (120°C). This low temperature helps the flavors infuse into the crackers without over-browning.
In a small bowl, combine the melted butter, Ranch dressing mix, dried dill weed, and onion powder. Stir until all ingredients are well mixed.
Place the oyster crackers in a large freezer bag. Pour the butter seasoning mixture over the crackers, seal the bag, and toss gently to coat.
Spread the seasoned crackers out in a single layer on two baking sheets (See note 1) Bake in the preheated oven for 10 minutes, then remove and stir the crackers gently. Place them back in the oven for another 5-10 minutes, keeping a close eye to avoid burning.
Once the crackers are golden and crisp, remove them from the oven and allow them to cool completely on the baking sheet. Store in an airtight container to maintain freshness.
Notes
Make sure the two baking sheets can fit in the oven at the same time! You can use one large baking sheet if needed, but I find that you can spread the crackers out into a single layer if you divide them across two smaller baking sheets. This allows them to bake evenly and get perfectly crisp.