Heat a splash of olive oil in a large skillet over medium heat until it shimmers and begins to gently sizzle.
Add chopped onion and minced garlic to the pan, stirring often. Cook until fragrant and translucent, about 2 minutes, filling the kitchen with a savory aroma.
Toss in the halved cherry tomatoes and any other vegetables you like. Sauté for about 3-4 minutes until the tomatoes start to burst and release their juices, creating a bright, fragrant mixture.
Pour in the vegetable broth and add your dry spaghetti, making sure the noodles are submerged in the liquid. Bring everything to a gentle boil, stirring occasionally to prevent sticking.
Reduce the heat slightly and let the pasta cook, stirring every few minutes. Cook until the noodles are al dente, about 10-12 minutes, and the broth has reduced into a glossy sauce that coats the pasta.
Once the pasta is tender and the liquid has thickened, stir in the chopped spinach. Cook for another 1-2 minutes until the greens have wilted and everything is heated through.
Turn off the heat and stir in the fresh lemon juice. Taste and adjust seasoning if needed. The dish should be bright, flavorful, and slightly saucy.
Let the pasta rest for a couple of minutes to allow the flavors to meld and the sauce to settle. Serve hot, garnished with herbs if desired, and enjoy this simple, comforting meal.