In a large serving bowl, stir together the Mexican crema, mayonnaise, lime juice, half of the cotija, half of the cilantro, and the chile powder. Set the bowl aside.
Heat a large skillet over medium-high heat. Add the oil and frozen corn. Spread the corn into an even layer and let it cook undisturbed for 3 minutes so a few kernels begin to brown.
Stir the corn and continue cooking for 5 to 7 minutes, stirring occasionally, until it is hot throughout and has scattered golden-brown spots.
Add the onion, serrano, garlic, salt, black pepper, and optional dried epazote. Cook for 2 to 3 minutes, stirring often, until the onion softens and the garlic is fragrant. Remove the skillet from the heat.
Add the warm corn mixture to the bowl with the creamy lime dressing. Toss until evenly coated. Taste and add a small pinch of salt or more lime juice if needed.
Spoon the esquites into bowls or onto a platter. Finish with the remaining cotija, cilantro, a dusting of chile powder, and lime wedges. Serve warm or at room temperature.