Take grilled cheese to the next level by using black forest ham and sharp white cheddar cheese, and add fresh arugula, red onion, and garlic aioli to the mix.
Lay down 4 slices of sourdough bread; spread each with garlic aioli.
Layer black forest ham, cheddar cheese, arugula, and red onion evenly over the 4 slices; top with other bread slices.
Preheat a griddle on medium-high heat; add olive oil and heat until shimmering (2 min).
Place all sandwiches on oiled griddle at once; allow to heat a few minutes until surface is golden brown; turn sandwiches over and repeat process on other side; serve warm.