Melt the butter in a medium saucepan over medium heat, letting it gently bubble and become fragrant. This should take about a minute or two. You want it to be melted but not browned, as we want to keep that lovely yellow color in our dip.
Add the finely chopped onion to the melted butter and cook, stirring frequently. You’re aiming for a soft and translucent texture, which usually takes around three to four minutes. The smell at this stage is heavenly!
Next, toss in the minced garlic and continue to stir for about one minute. It’s crucial to keep stirring to avoid burning the garlic, which can turn bitter. You want it aromatic and fragrant.
Sprinkle in the flour and continue stirring. Cook this mixture for about one minute to eliminate the raw flavor of the flour. You should see it thicken slightly and look silky.
Slowly pour in the half & half, stirring continuously to combine everything smoothly. You’ll notice the mixture beginning to turn creamy and luscious.
Now, add the thawed and drained spinach along with the chopped artichoke hearts. Stir occasionally, allowing the mixture to heat up and thicken, which should take about two more minutes. The colors will brighten as it heats!
Stir in the shredded Cheddar, Pecorino Romano, salt, pepper, and nutmeg. Keep stirring until the cheese melts completely, about one to two minutes. The dip should be smooth and creamy, with a rich flavor.
At this point, taste it with a chip and adjust the seasoning if necessary. Everyone’s palate is different, and this is your chance to make it just right!
Finally, transfer the dip to a serving bowl. The Best Spinach Artichoke Dip is best enjoyed warm, so serve it with a generous amount of tortilla chips around it for dipping.