01 -
Line the bottom and sides of a 6 to 8-quart slow cooker with a large piece of aluminum foil and spray it with nonstick cooking spray.
02 -
In a large bowl, whisk together milk, eggs, granulated sugar, 1 packet of au jus gravy mix, 1 packet of ranch seasoning mix, and panko breadcrumbs until uniformly blended.
03 -
Add the ground beef to the seasoned mixture and gently combine with clean hands until just incorporated; avoid overmixing to prevent toughness.
04 -
Transfer the meat mixture into the slow cooker and shape it gently into an oval form.
05 -
In a separate bowl or measuring cup, whisk together cold water, peperoncini juice, remaining packets of au jus gravy mix and ranch seasoning mix until fully combined.
06 -
Pour the prepared gravy evenly over and around the meatloaf. Arrange the whole peperoncini peppers on top.
07 -
Cover and cook on low for 5 to 6 hours or on high for 3 to 4 hours, until the internal temperature reaches 165°F.
08 -
Carefully lift the meatloaf out using two spatulas and transfer to a serving dish.
09 -
Strain the cooking liquid into a medium saucepan. In a small bowl, whisk cornstarch with water to form a slurry, then gradually whisk it into the simmering gravy. Cook for 1 minute until thickened, then remove from heat.
10 -
Slice the meatloaf and drizzle with the thickened gravy before serving.