In large skillet/saute pan, melt butter. Add chopped apples and brown sugar, stirring to coat. Saute over medium-high heat for 7-10 minutes, while mixing rest of batter. Allow to cool slightly.
While apples cook, in large bowl, beat eggs and oil until smooth.
Add sugar, vanilla, flour, spices and salt, and mix well.
Fold in apples, including syrup liquid from cooking.
Pour into greased 9x13 pan.
Bake at 350F degrees for 50-55 minutes.