Log in to Blogger, go to Layout and click on "Add a Gadget", and select it as "HTML/JavaScript type".
Now add this code in to the widget:

<script>

function rp(json) {

document.write('<ul>');



for (var i = 0; i < numposts; i++) {

document.write('<li>');


var entry = json.feed.entry[i];

var posttitle = entry.title.$t;

var posturl;



if (i == json.feed.entry.length) break;



for (var k = 0; k < entry.link.length; k++) {

if (entry.link[k].rel == 'alternate') {

posturl = entry.link[k].href;


break;

}

}



posttitle = posttitle.link(posturl);

var readmorelink = "(more)";

readmorelink = readmorelink.link(posturl);

var postdate = entry.published.$t;


var cdyear = postdate.substring(0,4);

var cdmonth = postdate.substring(5,7);

var cdday = postdate.substring(8,10);

var monthnames = new Array();

monthnames[1] = "Jan";

monthnames[2] = "Feb";

monthnames[3] = "Mar";


monthnames[4] = "Apr";

monthnames[5] = "May";

monthnames[6] = "Jun";

monthnames[7] = "Jul";

monthnames[8] = "Aug";


monthnames[9] = "Sep";

monthnames[10] = "Oct";

monthnames[11] = "Nov";

monthnames[12] = "Dec";




if ("content" in entry) {

var postcontent = entry.content.$t;

} else if ("summary" in entry) {

var postcontent = entry.summary.$t;

} else

var postcontent = "";


var re = /<\S[^>]*>/g;

postcontent = postcontent.replace(re, "");

document.write(posttitle);



if (showpostdate == true) document.write(' - ' + monthnames[parseInt(cdmonth,10)] + ' ' + cdday);



if (showpostsummary == true) {

if (postcontent.length < numchars) {


document.write(postcontent);

} else {

postcontent = postcontent.substring(0, numchars);

var quoteEnd = postcontent.lastIndexOf(" ");

postcontent = postcontent.substring(0,quoteEnd);

document.write(postcontent + '...' + readmorelink);

}

}


document.write('</li>');

}

document.write('</ul>');



}

</script>



<script>


var numposts = 7;

var showpostdate = false;

var showpostsummary = false;

var numchars = 100;

</script>



<script src="http://YOUR_BLOG.BLOGSPOT.COM/feeds/posts/default?orderby=published&alt=json-in-script&callback=rp"></script><br/><span style="font-size: x-small;"><a href="http://bloggerstop.net">Blogger Widgets</a></span>

The code in blue is what you have to change (replace the entire code in blue with your blog's address)
And the code in red, is optional to change.