A powder coating composition of a solid particulate film-forming mixture including (a) a carbamate group-containing polymer having a glass transition temperature of at least 30null C.; and (b) a curing agent having functional groups reactive with the carbamate functional groups of the polymer. Also provided is a multi-component composite coating composition characterized by a pigmented basecoat deposited from a pigmented film-forming composition and a substantially pigment-free top coat applied over the basecoat. The top coat is deposited from the powder coating composition. A method of forming a wrinkled coating on a substrate is further provided where a curable powder coating composition is prepared from a solid particulate film-forming mixture, applied to a substrate and thermally cured to form a continuous coating having a wrinkled surface. The solid particulate film-forming mixture includes (a) a carbamate functional group-containing polymer having a glass transition temperature at least 30null C., (b) a curing agent having functional groups reactive with the carbamate functional groups of the polymer (a), and (c) an amine salt of an acid catalyst. Coated substrates are also provided.