Prepare the spinach: If using frozen spinach, thaw completely and squeeze out as much water as possible using a fine mesh strainer. You want it very dry. If using fresh spinach, cook it down in a dry skillet over medium heat until fully wilted, then chop and squeeze out all excess moisture.
Add the spinach, spices, and cream cheese. Heat over medium heat until the cream cheese starts to melt and mix in with the spinach.
Add the tomatoes and shredded gouda. Heat over medium-low heat, stirring occasionally at first and more frequently as the cream cheese begins to soften. Keep the heat at medium or medium-low to avoid scorching.
Continue stirring until everything is fully melted together and the dip is smooth and creamy. If the dip is too thick, stir in a small splash of milk or a tablespoon of crushed tomato liquid to reach your preferred consistency.
Serve immediately as a stovetop dip, or transfer to a small baking dish, top generously with additional shredded gouda, and broil on high for 3 to 5 minutes until the cheese is melted and golden brown. Watch closely so it does not burn.
