Drain the pearl onions. In a saucepan over medium-low heat, slowly caramelize the sugar until golden brown (about 7-8 minutes). Add the cola to deglaze and simmer for 2-3 minutes until the sugar dissolves.
Add the pressed garlic and a few squirts of Tabasco if desired, then add the drained pearl onions.
Simmer over medium heat for 15 minutes until the liquid is reduced by about half.
Remove from heat and let cool, then add the parsley.