Combine flour and salt in a large bowl. Whisk milk, eggs, and melted butter together in a separate large bowl. Whisk egg mixture into flour mixture until smooth; cover and refrigerate for 1 hour. Strain the mixture into a clean bowl.

Heat a small nonstick skillet over medium heat; brush with butter. Pour 2 tablespoons of batter into the skillet and rotate to spread. Cook until the top is no longer wet and the bottom turns light brown, 1 to 2 minutes.

Flip the crêpe and cook until the other side is light brown, about 1 minute. Repeat for all batter.

Preheat oven to 350°F (175°C). Melt 3 tablespoons of butter in a skillet over medium-high heat; stir in garlic and thyme. Add chicken and cook until heated through, about 5 minutes. Stir in cream cheese until melted and smooth.

Spoon chicken mixture evenly on each crêpe and fold over. Place in a shallow casserole dish, overlapping slightly. Melt remaining butter and drizzle over crêpes.