Preheat the oven to 350 F (180 C).
Line a 12-cup muffin tin with paper liners. Set aside.

In a large bowl, combine the flour, ham, cheese, chives, baking powder, and salt.

In another bowl, lightly beat the egg.

Add the mustard, milk, and olive oil. Mix.

Pour into the center of the dry ingredients. Stir gently with a fork just until moistened.

Divide the batter into the prepared muffin tin using a spoon.

Bake in the preheated oven for 20 to 25 minutes.

Check for doneness by inserting a toothpick into the center of a muffin: it should come out clean.

Once out of the oven, let the muffins rest for 5 minutes before transferring them to a cooling rack.