Microwave the frozen hash browns on high for 4 minutes to partially thaw. Or else let them sit on the counter for a few hours before you are ready to use them.
Combine the hash browns, green pepper, green onions and ham in a slow cooker and stir to mix. Save some green onions for the garnish (about 1 tablespoon).
Blend the cream cheese and milk together and then heat in a microwave for 1 to 2 minutes or until smooth when whisked. Add the mustard and spices and stir to blend.
Pour cream cheese mixture evenly over hashbrown mixture. DO NOT STIR.
Cover and cook on low heat for 5 to 6 hours or until the potatoes are tender. Carefully stir. Garnish with the remaining green onions and serve hot.
Notes
If you can't find garlic pepper, you can use a garlic seasoning.