Pour olive oil into a small frying pan over medium-low heat. Add garlic and spices and cook, stirring often until fragrant, 1 to 2 minutes, being careful not to scorch the garlic. Scrape the mixture into a slow-cooker (at least 5 qt.).
Add broth, carrots, eggplant, zucchini, cauliflower, onion, stewed tomatoes (with juices), garbanzos, currants, almonds, and salt, and stir to combine.
Cover slow-cooker and cook on high until vegetables are tender to bite and flavors are blended, 8 to 9 hours.
Ladle about 3 cups of the vegetable mixture into a blender. Holding lid down with a towel and taking care to avoid steam, whirl until smooth. Return purée to slow-cooker and stir to blend. Ladle stew into a tureen or individual bowls.