Sauté Aromatics:

1. Heat olive oil in a large saucepan over medium heat.
2. Add diced onion and sauté for 5-7 minutes until softened.
3. Add minced garlic and cook for 30 seconds, stirring frequently.

Cook Tomato Paste:

1. Stir in the tomato paste and cook for 1-2 minutes to deepen its flavor.

Add Remaining Ingredients:

1. Lower the heat to low. Pour in the crushed tomatoes, scraping the pan to release any cooked-on bits.
2. Stir in brown sugar, apple cider vinegar, kosher salt, ground mustard, ground cloves, and allspice. Mix well.

Blend the Mixture:

1. Use an immersion blender to puree the mixture until smooth directly in the saucepan. Alternatively, transfer the mixture to a blender and puree in batches.

Simmer:

1. Bring the ketchup to a gentle simmer. Let it simmer uncovered for 1½ to 2 hours, stirring occasionally, until it thickens to your desired consistency.
2. Use a splatter screen if necessary to prevent messes.

Smooth the Texture (Optional):

1. For an ultra-smooth ketchup, pass the mixture through a fine mesh sieve before cooling.

Cool and Store:

1. Let the ketchup cool slightly before transferring it to a glass jar or airtight container.
2. Refrigerate for up to 1 month or freeze for up to 6 months.