I found this in my SIL's Betty Crocker cookbook awhile back and have been wanting to try it. Maybe this is what you're looking for?

Oatmeal-Chocolate Clusters

(Betty Crocker)

1 pkg (6 ounces) semisweet chocolate chips
1/3 cup butter or margarine
16 large marshmallows
½ tsp vanilla
2 cups rolled oats
1 cup flaked coconut

Heat chocolate chips, butter, and marshmallows in 3-quart saucepan over low heat, stirring constantly, until smooth; remove from heat. Mix in vanilla, oats and coconut. Drop mixture by teaspoonfuls onto waxed paper and shape into clusters with hands. Refrigerate until firm, about 30 minutes. About 3½ dozen candies.

Bran-Chocolate Clusters: Substitute ½ cup whole bran cereal for ½ cup of the oats.

Here's another. Just calls for regular marshmallows but maybe she altered the recipe to use mini colored ones?

If she actually baked them in an oven, this isn't it.

Here is a link that might be useful: No Bake Cookies