Combine 2 tablespoons water, honey, and thyme in a small microwave-safe bowl. Microwave at HIGH for 20 seconds or until honey is dissolved; cool completely.
Combine sliced cucumber, honey mixture, and next 4 ingredients (through Grand Marnier) in a blender. Add 1 1/4 cups ice cubes (about 12 large cubes); blend until cucumber is pureed and ice is slushy. Pour into glasses; garnish with cucumber slices.