Start by gathering all your ingredients. Grab your slicing knife and cutting board, and slice your heirloom or Roma tomato. Set it aside. Shred your aged cheddar cheese if you haven't done so already. Freshly shredded cheese melts better than pre-packaged stuff. I promise; it's worth the extra two minutes.

In a small bowl, combine the mayonnaise and basil pesto. Swirl them together until they are well blended. You can also add a pinch of salt here if you like. This spread is vital, as it adds creaminess and flavor! Pro tip: Taste it to make sure it hits the flavor jackpot.

Spread the pesto-mayonnaise mixture generously on one side of each slice of bread. On one slice, layer your shredded cheese, followed by the sliced tomato, and then add fresh arugula. Sprinkle a tiny bit of freshly cracked black pepper on top of the arugula for an extra kick. Top it off with the second slice of bread, spread-side down.

Preheat your grill or pan over medium heat. You want it hot enough to toast the bread, but not so hot that it burns before the cheese melts. If you're like me and don't trust your instincts, just do the ol' bread water sizzle test. If it makes that sound, you’re golden.

Carefully place your sandwich onto the grill. Grill for about three to four minutes on one side until it’s golden brown. If you have a grill press, it can help the melting process. Flip it over and grill on the other side until the cheese is gooey and melty—usually, just another three to four minutes.

Once both sides are crisp and the cheese is gooey, carefully remove your sandwich from the grill. Let it rest for about a minute before slicing it in half. A crispy sandwich deserves a solid resting period to maintain its crunch.