Cook the bacon in a large skillet over medium-high heat until crispy, about 8 to 10 minutes, turning occasionally. Transfer to a paper towel-lined plate, let cool, then chop into bite-sized pieces. Reserve 1 and a half tablespoons of bacon grease in a small bowl for the dressing.

Bring a large pot of salted water to a boil and cook pasta shells according to package directions until al dente, about 8 to 10 minutes.

Halve the grape tomatoes lengthwise and cut the cheddar into quarter-inch cubes. Place both in a large mixing bowl and set aside.

Drain the cooked pasta and immediately rinse under cold running water until completely cooled, stirring gently. Add the cold peas to the chilled pasta and stir to combine.

In a medium bowl, whisk together the mayonnaise and milk until smooth. Add the dill, parsley, chives, garlic powder, onion powder, mustard powder, salt, and pepper. Whisk until evenly combined. Add the fresh lemon juice and reserved bacon grease last and whisk to incorporate.

Add the chilled pasta and peas to the bowl with the tomatoes and cheese. Pour the ranch dressing over everything and add the chopped bacon. Gently toss until all ingredients are evenly coated. Refrigerate for at least 1 hour before serving.