Manipulating a DTFT into Correct Form

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I am trying to get the DTFT $H(\Omega)$ of $h[n]=\delta[n]+\delta[n-1]$.

I used some DTFT pairs and I have:

$$H(\Omega) = 1 + e^{-j\Omega}$$

However, the answer provided is:

$$H(\Omega)=2e^{-j\Omega/2}\cos(\Omega/2)$$

So I am wondering, how can I finagle the calculated $H(\Omega)$ into the solution's form?

Thanks.

Note: $j:=i$