Kat and Ari live for "cookie time" with Grandpa and his dog, Biscuit. Today, though, they can't wait for the cookies to bake, "so they buil[d] a time machine." Though it's made of cardboard and marker, it hurtles them through a rainbow-tinted wormhole, depositing them in the near future. Unfortunately, something went wrong and the cookies have already been eaten. Something goes wrong with every leg of their ensuing travels, sending them too far back, then too far forward again, when they land in a gorgeously rendered, distant sf setting. Here, they find the dream: a Cookie Time store that requires no waiting. But they realize the most important ingredient is missing. Sima once again flexes their conceptual genius in a delightful adventure that will pull kids in from the jump. And if cookies and time travel aren't enough, the soft, pastel color palette is so inviting, as are all the sweet side characters and details. A heartwarming message about family is icing on the cookie.

Two children find themselves on a time-traveling adventure while they wait for Grandpa's cookies to come out of the oven.When Kat and Ari build a time machine, they set it for "the future, to just after the cookies [are] finished baking." But they end up bouncing through time-to that evening, when the cookies have already been eaten, then back to their very first time baking with Grandpa as young tots. Then they find themselves in the very distant future. Through this journey, Kat and Ari realize that waiting's much easier when you lean into enjoying the passage of time together. Soft pastel colors convey this message deftly. Speeding through time, the children fly past an ombre rainbow. A wash of blue instantly indicates a nighttime scene lit by the light of Grandpa's front porch. The far-off future includes plenty for readers to take in: a house with legs, a dragon-inspired airplane, and special tubes through which townspeople float through in place of streets. Effective use of panels moves the narrative along and gives it a graphic novel–esque feel. This playful story examines a child's natural impatience while showcasing how very rewarding and special waiting can be. Grandpa has light brown skin, while Kat has tan skin; Ari presents Black.A read worth waiting for. (Picture book. 4-6)