Season the cubed chicken thighs and heat the olive oil in a large skillet over medium heat. Add garlic and heat until just lightly golden brown. Add the chicken, cover, and cook for 5-7 minutes, or until thickest part of the cube is no longer pink on the inside. Remove from heat, keep covered, and set aside. While chicken is cooking, combine the crepe ingredients into a bowl and mix together well with a wire whisk. The consistency of the batter will be runny at first and it should be - we are making crepes, not pancakes! However, it will thicken slowly (if it becomes too thick while you are cooking the crepes, add a splash or two of extra milk to thin it out). In a medium skillet, heat the 1/2 T butter and coat the entire pan with it. Using either a measuring cup or ladle with a spout, slowly pour some of the batter into the skillet until it covers the entire bottom. If you pour too fast, you'll end up with a ton of splattered batter (hey, that rhymed) and very uneven-looking crepes. Cook over medium low heat until the edges become slightly dry, about 45 seconds. With a spatula, check to make sure the crepe is starting to turn a golden brown on the bottom. If so, it's ready to flip onto the other side. Cook for about another 30 seconds or until the bottom side is golden brown. Transfer onto a plate and cover, so that the crepes stay moist and warm. Repeat the process until all the batter has been used. Prepare the fresh rosemary cream after the crepes and chicken are completely cooked. In a small saucepan, heat the butter over medium low heat until melted and add the half & half, whisking to make sure the cream doesn't burn. Next, add the fresh chopped rosemary and salt & pepper and whisk to mix. When the cream barely starts to boil around the edges, stir in the cornstarch (or flour) and water mixture and whisk briskly so that the sauce begins thicken. Cook for another minute or so, or until your sauce thickens well. Don't worry if it's a little runny at first; it will thicken after removing it from the heat. Assemble your crepes by placing a spoonful or two or chicken (depending on how full you want your crepes) in the center of each crepe, drizzle a little bit of rosemary cream on the inside if you like, roll together, and place on a plate. Continue until all crepes have been assembled. Ladle a generous amount of the rosemary cream sauce on top of each serving, garnish with extra fresh rosemary sprigs, and enjoy!