Kristina Morales and the Bayou Shufflers keep it sweet and lowdown on the band’s debut CD, which takes its cue—as well as its title—from a Fats Waller tune. Digging in with an earthier sound than she utilized on her Wonderful World solo CD, Morales lets loose, her light soprano loosened up by a wide vibrato and the kind of guttural growl these early jazz and blues songs deserve. Gone, too, is her conservatory strictness—the lyrics to “You Rascal You” could have come straight from a Storyville catfight. The six-piece band, however, is with her every step of the way. Clarinetist Gregory Agid begins his own embellishments right from the opening title tune, but he really comes to his own on “I Found a New Baby,” a 1926 composition that also has cornetist Kevin Louis and trombonist Michael Watson both getting in swift, soaring solos. On occasion (okay, on the snoozily correct 1929 tune “Pagan Love Song” and the campy “Cuban Love Song,” from 1931), the whole getup can seem a little forced. But overall, this is a playful trip down the music’s memory lane. Even the one song less than 60 years old, the instrumental “October” by bassist Nathan Lamberston (who also contributed a song to Morales’ solo debut), gently updates a rumba, letting his bandmates swing in the style to which they have become accustomed.