Make the white widow salsa: Preheat oven to 400°F with rack in highest position. Line a baking sheet with aluminum foil.

Toss habanero chiles and garlic in oil, and spread evenly on prepared baking sheet. Roast on upper rack until mixture softens and blackens, 12 to 15 minutes. Set aside, and let cool for 5 minutes.

Whisk together milk, 6 tablespoons water, crema, mayonnaise, and cream cheese in a medium bowl until thoroughly incorporated.

Place cream cheese mixture, roasted chile mixture, cilantro, and salt in a blender; process until smooth, about 25 seconds.

Make the tacos gobernador: Place poblano chile directly on an open flame of a stovetop over medium-high. Cook until skin is completely blackened, about 8 minutes, turning chile occasionally using a pair of tongs. (Alternatively, broil chile until blackened, about 10 minutes, turning occasionally.) Place chile in a small bowl, and cover tightly using plastic wrap. Let stand until cool enough to handle, about 10 minutes. Uncover chile; remove and discard charred skins and seeds. Cut chile into strips; set aside.

Cook butter and garlic in a large skillet over medium, stirring often, until butter is melted and garlic is soft, about 3 minutes. Add shrimp pieces and salt; cook, stirring constantly, until shrimp turn light pink, 3 to 4 minutes. Remove from heat, and stir in charred poblano strips.

Place a dry medium-size nonstick skillet or comal over medium heat (or use your grill). Add tortillas; cook until pliable, 25 to 30 seconds, flipping halfway through cooking time. Place warmed tortillas on a clean work surface; cover using a clean dish towel, and keep warm.

Open bottom vent of grill completely. Light charcoal chimney starter filled with briquettes, and wait until briquettes are covered with gray ash, about 20 minutes. (Never use charcoal lighter fluid to start a charcoal fire; it will give grilled foods a chemical taste.)

While briquettes light, fill a tortilla with 2 tablespoons shrimp mixture and 2 tablespoons cheese. Fold filled tortilla in half, and secure by threading a wooden pick along edge of tortilla. Repeat process with remaining tortillas, shrimp mixture, and cheese. Cover using a dish towel until ready to cook.

Pour briquettes onto bottom grate of grill, and spread in an even layer. Coat top grill grate with oil; place on grill. Cover grill with lid, and preheat for about 4 minutes. Remove grill lid, and place half of tacos on oiled grate. Grill, uncovered, until tortillas crisp up, cheese melts, and tacos pick up some flavor from grill, about 3 minutes, carefully flipping tacos halfway through grilling time. Transfer to a large plate, and repeat process with remaining tacos.

Serve tacos with white widow salsa and lime wedges.