After trying a series of enriched doughs (with milk, then egg, as well as sugar), I went back to my original breakfast bun recipe, but this time changed my baking technique. Having recently made baguettes, I attempted a more crusty bun by brushing the dough balls with water prior to baking, and spraying water into the oven a few times during the first six minutes to create steam.
The buns came out great, with good color and flavor. The crust had a bit of resistance, but they were not truly crusty after 15 minutes at 375 °F (with convection). I wasn’t surprised: this temperature is probably not high enough and my relatively large oven probably requires more aggressive measures for introducing steam. Adding a bit of sugar or malt powder may also help.