Preheat oven to 250 degrees Fahrenheit.
In a 9×13” baking dish, add garlic and ¾ cup olive oil, place plum tomatoes, cut side up in the baking dish. Mix together, salt, sugar and oregano then sprinkle over tomatoes evenly. Carefully drizzle remaining ¾ cup of the olive oil over the tomatoes.
Bake for one hour, carefully flip the tomatoes so cut side is down. Place back into oven for one hour, carefully flip the tomatoes so the cut side is facing up. Place into oven for one more hour.
Remove from oven and allow to cool. Carefully remove the tomatoes and place into a storage container deep enough to hold tomatoes and reserved oil. Strain the oil, reserving the liquid, you will pour the strained olive oil over the tomatoes, cover and refrigerate, saving for later use. It is best if the tomatoes are covered completely in the oil.
Remove the tasty bits from your strainer and place into a mixing bowl with the softened butter. You should have the confit garlic cloves, herbs and small bits of tomato.
Mix thoroughly using the back of a wooded spoon. You may want to add reserved olive oil one teaspoon at a time for additional flavor and desired consistency
Seal tightly and refrigerate.