Day old bread works great for making crostini. Your baking time may need less time in the oven because the bread will be a little more dryer than fresh bread.
You can also use avocado oil or melted butter instead of olive oil, if that is your preference.
Feel free to get creative with the herbs and spices you use in this recipe. Some popular options include rosemary, thyme, garlic powder, or even a sprinkle of chili flakes for some heat.
For a cheesy twist, sprinkle some grated parmesan on top of the crackers before baking them.