Heat a grill or smoker for two-zone cooking with one hot side for searing. Heat a large cast iron grill over the hot side and add some olive oil and the onions with a heavy pinch of salt. Cook until the onions are softened and beginning to brown, about 10 minutes. Add the garlic and cook until fragrant, a minute more.
Add the crushed tomatoes, a three-finger pinch of salt. Italian seasoning and some torn basil leaves to the skillet and cook until simmering, about 4 minutes. While the tomato mixture comes to a simmer, crack the eggs into small bowls — this makes adding the eggs to the skillet easier.
Remove the skillet from the grill and use the back of a spoon to make 6 shallow wells in the tomato mixture. Quickly add one egg to each well and return the skillet to the indirect side of the grill. Cover the grill and cook until the eggs are set to your liking — we go for about 5 minutes for a jammy yolk.
Remove the skillet from the grill and toast the baguette. Serve the eggs with a chiffonade of basil, olive oil, and salt along with the toasted baguette.